Support bare interpolation in attribute selectors.

Closes #331
Declare invert().
Merge branch 'stable'
Support -moz-element.

Closes #355
Properly convert empty lists.

Closes #352
Move from FSSM -> guard/listen.

Closes #351
Merge branch 'stable'

Conflicts:
	test/sass/conversion_test.rb
Bump VERSION to 3.1.16.
Merge branch 'stable'

Conflicts:
	VERSION
	doc-src/SASS_CHANGELOG.md
Fix Tree#inspect on Ruby 1.9.

1.9's #inspect defaults to #to_s, which fails on non-static trees.

Closes #367
Fix the Listen plugin.

Closes #372
Closes #370
Closes #362
Merge branch 'stable'

Conflicts:
	doc-src/SASS_CHANGELOG.md
Add null literal.
Make keyword argument parsing stricter.

Closes #328
Merge remote branch 'origin/master'

Conflicts:
	doc-src/SASS_CHANGELOG.md
Merge remote branch 'origin/stable' into stable

Conflicts:
	doc-src/SASS_CHANGELOG.md
Merge branch 'stable'
Fix Dir.glob with backslash paths on Windows.
Use my listen repo for the time being.

My repo contains a few bug fixes that aren't in the main repo yet.
Fix listener for nested dirs.

Closes #362