Support nested media queries. Closes #931
Fixed bug with hash values in `@media` and css-like syntax
misc refactoring
more complex test
Merge branch 'pr/1540' into rc-0.46

* pr/1540:
  more complex test
  misc refactoring
  Fixed bug with hash values in `@media` and css-like syntax
  Support nested media queries. Closes #931

Conflicts:
	test/cases/media.complex.css
	test/cases/media.complex.styl
Added docs for nested media queries