Proper parsing of the media queries
Support the hash objects in `define`. Fixes #1286
Support comments
Don't generate empty media queries
Better toString
Added tests for `define`
Merge branch 'pr/1444' into rc-0.43

* pr/1444:
  Added tests for `define`
  Support the hash objects in `define`. Fixes #1286
Merge branch 'pr/1453' into rc-0.43

* pr/1453:
  Better toString
  Don't generate empty media queries
  Support comments
  Proper parsing of the media queries
Fixed bug with literal as value of the variable in media query
Added docs on new MQ features