Fix clippy warnings (alfg#88)

* chore: fix clippy warnings

* Update readme with clippy usage.

* fix fmt warnings.

README.md

@@ -103,6 +103,22 @@ With print statement output.
 cargo test -- --nocapture
 ```
 
+#### Run Cargo fmt
+Run fmt to catch formatting errors.
+
+```
+rustup component add rustfmt
+cargo fmt --all -- --check
+```
+
+#### Run Clippy
+Run Clippy tests to catch common lints and mistakes.
+
+```
+rustup component add clippy
+cargo clippy --no-deps -- -D warnings
+```
+
 #### Run Benchmark Tests
 ```
 cargo bench

src/mp4box/emsg.rs

@@ -26,7 +26,7 @@ impl EmsgBox {
             4 + // id
             Self::time_size(version) +
             (scheme_id_uri.len() + 1) as u64 +
-            (value.len() as u64 + 1) as u64
+            (value.len() as u64 + 1)
     }
 
     fn time_size(version: u8) -> u64 {

src/mp4box/meta.rs

@@ -17,10 +17,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MetaBox {
 
         let (version, _) = read_box_header_ext(reader)?;
         if version != 0 {
-            return Err(Error::UnsupportedBoxVersion(
-                BoxType::UdtaBox,
-                version as u8,
-            ));
+            return Err(Error::UnsupportedBoxVersion(BoxType::UdtaBox, version));
         }
 
         let mut ilst = None;

src/track.rs

@@ -427,7 +427,7 @@ impl Mp4Track {
     fn sample_offset(&self, sample_id: u32) -> Result<u64> {
         if !self.trafs.is_empty() {
             if let Some((traf_idx, _sample_idx)) = self.find_traf_idx_and_sample_idx(sample_id) {
-                Ok(self.trafs[traf_idx].tfhd.base_data_offset as u64)
+                Ok(self.trafs[traf_idx].tfhd.base_data_offset)
             } else {
                 Err(Error::BoxInTrafNotFound(self.track_id(), BoxType::TrafBox))
             }