Replace docs.serde.rs links

rust-fuzz/cargo-fuzz#317

This code is from September 2018, at which point serde_json supported
rustc back to 1.15. repr(transparent) stabilized in 1.28. Today the
minimum required compiler is 1.36, so repr(transparent) is okay to use.

Hide repr attribute from documentation

Support 128-bit integers in to_value

    error: non-binding `let` without a type annotation
        --> src/de.rs:1712:9
         |
    1712 |         let _ = name;
         |         ^^^^^^^^^^^^^
         |
         = help: consider adding a type annotation or removing the `let` keyword
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped
         = note: `-D clippy::let-underscore-untyped` implied by `-D clippy::pedantic`

    error: non-binding `let` without a type annotation
        --> src/de.rs:2190:9
         |
    2190 |         let _ = name;
         |         ^^^^^^^^^^^^^
         |
         = help: consider adding a type annotation or removing the `let` keyword
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
      --> src/map.rs:51:17
       |
    51 |                 let _ = capacity;
       |                 ^^^^^^^^^^^^^^^^^
       |
       = help: consider adding a type annotation or removing the `let` keyword
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
       --> src/value/de.rs:312:9
        |
    312 |         let _ = name;
        |         ^^^^^^^^^^^^^
        |
        = help: consider adding a type annotation or removing the `let` keyword
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
       --> src/value/de.rs:803:9
        |
    803 |         let _ = name;
        |         ^^^^^^^^^^^^^
        |
        = help: consider adding a type annotation or removing the `let` keyword
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
      --> tests/lexical/num.rs:26:5
       |
    26 |     let _ = x;
       |     ^^^^^^^^^^
       |
       = help: consider adding a type annotation or removing the `let` keyword
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped
       = note: `-D clippy::let-underscore-untyped` implied by `-D clippy::pedantic`

    error: non-binding `let` without a type annotation
      --> tests/lexical/num.rs:31:5
       |
    31 |     let _ = y + x;
       |     ^^^^^^^^^^^^^^
       |
       = help: consider adding a type annotation or removing the `let` keyword
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
      --> tests/lexical/num.rs:48:5
       |
    48 |     let _ = x & T::ZERO;
       |     ^^^^^^^^^^^^^^^^^^^^
       |
       = help: consider adding a type annotation or removing the `let` keyword
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
      --> tests/lexical/num.rs:61:5
       |
    61 |     let _ = x.pow10(5);
       |     ^^^^^^^^^^^^^^^^^^^
       |
       = help: consider adding a type annotation or removing the `let` keyword
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
      --> tests/lexical/num.rs:62:5
       |
    62 |     let _ = x.to_bits();
       |     ^^^^^^^^^^^^^^^^^^^^
       |
       = help: consider adding a type annotation or removing the `let` keyword
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
      --> tests/lexical/num.rs:66:5
       |
    66 |     let _ = x.to_bits() & T::SIGN_MASK;
       |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       |
       = help: consider adding a type annotation or removing the `let` keyword
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
      --> tests/lexical/num.rs:67:5
       |
    67 |     let _ = x.to_bits() & T::EXPONENT_MASK;
       |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       |
       = help: consider adding a type annotation or removing the `let` keyword
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
      --> tests/lexical/num.rs:68:5
       |
    68 |     let _ = x.to_bits() & T::HIDDEN_BIT_MASK;
       |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       |
       = help: consider adding a type annotation or removing the `let` keyword
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
      --> tests/lexical/num.rs:69:5
       |
    69 |     let _ = x.to_bits() & T::MANTISSA_MASK;
       |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       |
       = help: consider adding a type annotation or removing the `let` keyword
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
        --> tests/test.rs:1977:5
         |
    1977 | /     let _ = json!([
    1978 | |         <Result<(), ()> as Clone>::clone(&Ok(())),
    1979 | |         <Result<(), ()> as Clone>::clone(&Err(()))
    1980 | |     ]);
         | |_______^
         |
         = help: consider adding a type annotation or removing the `let` keyword
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped
         = note: `-D clippy::let-underscore-untyped` implied by `-D clippy::pedantic`

    error: non-binding `let` without a type annotation
        --> tests/test.rs:1983:5
         |
    1983 | /     let _ = json!({
    1984 | |         "ok": <Result<(), ()> as Clone>::clone(&Ok(())),
    1985 | |         "err": <Result<(), ()> as Clone>::clone(&Err(()))
    1986 | |     });
         | |_______^
         |
         = help: consider adding a type annotation or removing the `let` keyword
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
        --> tests/test.rs:1989:5
         |
    1989 | /     let _ = json!({
    1990 | |         (<Result<&str, ()> as Clone>::clone(&Ok("")).unwrap()): "ok",
    1991 | |         (<Result<(), &str> as Clone>::clone(&Err("")).unwrap_err()): "err"
    1992 | |     });
         | |_______^
         |
         = help: consider adding a type annotation or removing the `let` keyword
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

    error: non-binding `let` without a type annotation
        --> tests/test.rs:1995:5
         |
    1995 |     let _ = json!({ "architecture": [true, null] });
         |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
         |
         = help: consider adding a type annotation or removing the `let` keyword
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_untyped

Fix message duplication between error Display and source()

Caught by test_partialeq_number:

    thread 'test_partialeq_number' panicked at 'assertion failed: `(left == right)`
      left: `-3.4028235e38`,
     right: `Number(-3.4028235e38)`', tests/test.rs:2033:5

Eliminate f32-to-f64 casting in arbitrary_precision mode

    error: the borrowed expression implements the required traits
     --> tests/regression/issue1004.rs:6:38
      |
    6 |     let value = serde_json::to_value(&float).unwrap();
      |                                      ^^^^^^ help: change this to: `float`
      |
      = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow
      = note: `-D clippy::needless-borrow` implied by `-D clippy::all`

Document to_writer only writes valid UTF-8 strings