Merge pull request #1 from sass/main

Move var and variant functions to extension functions directory…

Add sass-string dart to compile to sass-string executable.

Uncomment examples.

Include extension in string sass module.

Fix returning reversed in set-bracketed(), set-separator(), and…

Add files to compile sass.

Add helpers to extension.

Stop emitting mixed-decls in a bunch of unnecessary cases (sass#2342)