Fixing a bug in the `comparable` built-in.
Returning the wrong type of node from `saturation` and `lightness`.
Fixing a bug in the expansion of selector groups with back-refs.
'Nuther tweak to the backref-in-selector-group fix. Not quite done yet.
Finishing up the backref-in-selector-groups bugfix.
Un-requiring a semicolon after mixin content blocks.
Getting numbers to print out like canonical Sass.
Initial implementation of @keyframe directives
Handling some BOMs.
Reporting an error on all BOMs except UTF-8.
Merge pull request #93 from enriclluelles/feature/keyframes

Everything seems to work. I'll make a couple of touch-ups myself, and see if the code can be generalized to handle all similarly structured directives.
Merge branch 'master' into refactor-2012.12.05
Simplifying the classes.