TODO support in Atom

Adds syntax highlighting to TODO, DONE, FIXME, CHANGED, XXX, IDEA, HACK, NOTE, REVIEW, NB, BUG, QUESTION, COMBAK, TEMP, DEBUG, OPTIMIZE, and WARNING in comments and text in Atom.

Originally converted from the TODO TextMate bundle.

Contributions are greatly appreciated. Please fork this repository and open a pull request to add snippets, make grammar tweaks, etc.