0.5.1

Feature enhancements:

* Added or improved file type filtering for vim.
* [FEATURE #34](https://github.com/BurntSushi/ripgrep/issues/34):
  Add a `-o/--only-matching` flag.
* [FEATURE #377](https://github.com/BurntSushi/ripgrep/issues/377):
  Column numbers can now be customized with a color. (The default is
  no color.)
* [FEATURE #419](https://github.com/BurntSushi/ripgrep/issues/419):
  Added `-0` short flag option for `--null`.

Bug fixes:

* [BUG #381](https://github.com/BurntSushi/ripgrep/issues/381):
  Include license text in all subcrates.
* [BUG #418](https://github.com/BurntSushi/ripgrep/issues/418),
  [BUG #426](https://github.com/BurntSushi/ripgrep/issues/426),
  [BUG #439](https://github.com/BurntSushi/ripgrep/issues/439):
  Fix a few bugs with `-h/--help` output.
