Skin installable under Frodo

Status update:

I fixed the most pressing issues with the skin under Frodo. 
This makes the skin installable on a clean Frodo RC3 system.
This also breaks backwards compatibility with previous versions.

Todo: 

I created a list of current issues that i think need to be adressed before the skin is Frodo-complete. (https://github.com/kibje/skin.neon/issues?state=open)