Merge #710: rustfmt: Use show_parse_errors

9e8505d rustfmt: Use show_parse_errors (Jamil Lambert, PhD)

Pull request description:

  Following on from the [comment in rust-bitcoin #3006](rust-bitcoin/rust-bitcoin#3006 (comment)),
  Quoting tcharding (link removed to prevent spamming rustfmt PR):

  > There are no behaviour changes with this patch applied.
  >
  > In rust-lang/rustfmt 5961 the `hide_parse_errors` was changed to `show_parse_errors` with default `true`.
  >
  > Since we run the formatter with nightly we are getting the following warning
  >
  > Warning: the `hide_parse_errors` option is deprecated. Use `show_parse_errors` instead
  >
  > Rename the variable and keep the default value `true`.

ACKs for top commit:
  tcharding:
    ACK 9e8505d
  apoelstra:
    ACK 9e8505d

Tree-SHA512: 36a89750e8759f23fe4c92bd6684f055c9f5c097d5e6365d1d296240d84ab2a2b21879dba286035d7533b197d9d88d8e006dc8b2d292d512ed77a58ddf294624

rustfmt.toml

@@ -65,7 +65,7 @@ color = "Auto"
 unstable_features = false
 disable_all_formatting = false
 skip_children = false
-hide_parse_errors = false
+show_parse_errors = true
 error_on_line_overflow = false
 error_on_unformatted = false
 ignore = []