Fixes an issue regarding \!important and spaces
Adds tests for previous commit
Adding -webkit-mask-position to 0 0 swapout exceptions
Reming empty rules with a media query

https://github.com/yui/yuicompressor/commit/94c028a8c33a6c859d9ddd584a74ed40014395bf
Changes to 'zeros', and code to make some stuff case-insensitive
Updates special IE6 case space retention thingy
Force function, directive and pseudo names to lowercase
Fixes @charset