Merge branch 'release/1.20' into develop

* release/1.20:
  Update changelog
  Bump copyright year to 2013
  Bump version to v1.20
Move CSS @import statements to top of combined file

Thanks to jhuriez for pointing this out and for the basis of this patch.

See #39.
Bump version to v1.21
Update changelog
Merge branch 'release/1.21'

* release/1.21:
  Update changelog
  Bump version to v1.21
  Move CSS @import statements to top of combined file