Add branch-alias

This way people can require "0.3.*" and get stable vs unstable
versions depending on their minimum-stability, without having to
deal with the pains of dev-master.
Merge pull request #368 from igorw/patch-1

Add branch-alias
Add support for media query variables #335
add test for variable in media
add unit function, fixes #367
support nested interpolations #345
support interpolation inside of selectors fixes #370 #372 #369 #356
performance boost for selector parsing with interpolations
fixed a typo
Merge pull request #381 from nyordanov/master

Minor typo in toRGB($color)
version bump
remove mysterious line, fix #384
Update docs.md

Changed typo "an" -> "and"
Merge pull request #389 from quasipickle/patch-1

Update docs.md
Add precision to lib_round
Fixed Deprecation in PHP6

Accessing Strings via Curly brackets will be deprecated in PHP6
http://php.net/manual/de/language.types.string.php#example-58 (above this example)

also i don't think it is as readable as brackets
Merge pull request #400 from Handfeger/master

Using square brackets instead of curly brackets to access string content
Fix typo in docs/docs.md

constrast -> contrast
Merge pull request #406 from TimWolla/patch-1

Fix typo in docs/docs.md
Adding viewport directives