Update gitignore.
More permissive matching.

- Match keywords without trailing colons.
- Match keywords without leading comment slashes //.
- Ignore keywords in "quotes".
- Make a "best effort" to supply some kind of description even if the keyword is alone on the line.
- Handle keywords even if they're not the first item on the line.
- Refine regex and add capture groups to simplify parsing on the Objective-C side.
- Accidental auto-format related style changes. (Sorry about the massive diff.)