Sopel-boorus

Added:
* Post ID number in `danbooru`/`gelbooru` output (15)

Changed:
* Don't append `rating:general` to `md5:` queries (16)
* Cleaned up `search_tags()` abstraction (11)

Fixed:
* Danbooru search handling was broken ([10][])

[10]: https://github.com/dgw/sopel-boorus/pull/10

Fixed:
* URL pattern for `danbooru` became *too* strict ([9][])

[9]: https://github.com/dgw/sopel-boorus/pull/9

Changed:
* URL patterns are stricter ([8][])

Fixed:
* Unescape HTML entities in tag names ([7][])
* Corrected post rating colors ([3][])

[3]: https://github.com/dgw/sopel-boorus/pull/3
[7]: https://github.com/dgw/sopel-boorus/pull/7
[8]: https://github.com/dgw/sopel-boorus/pull/8

Fixed:
* Handle more error cases ([1][])

[1]: https://github.com/dgw/sopel-boorus/pull/1

First release of `sopel-boorus` plugin collection.

Launch plugins are `danbooru` and `gelbooru`.