Renamed "CSS" to "Style" as discussed with void256

This renames the CSS related part of the system to be known as "styles". Since its not a proper CSS file as a browser would use it, it's a nifty-specific CSS system.

The original files regarding default CSS handlers and systems have been left untouched (like the parsers and external libraries).

Javadocs have been changed accordingly as well.
Merge pull request #302 from spaceemotion/2.0

Renamed "CSS" to "Style" as discussed with void256