Move CSS files out of src/

The main reason is that our CSS files are currently not very well sorted and often strewn across multiple directories, so the idea is that while moving them I can sort the files properly and move some content around to.

Pros:

• We want most of our files out of src/ to get them out of the big eval() anyways.
• All CSS files are at one place instead of strewn around, often only single files in a directory.

Cons:

• Some CSS files are next to the only JS/TW file where they are required for, moving them breaks that connection
  • Can be partly mitigated by proper naming/documentation
• We need to move around a lot of files
• Git history will be less than perfect because I also plan to split/merge/rearrange the contents of some files.
  • Making moving files and modifying content separate commits mostly mitigates this.

Tasks

• Decide on directory name: css/
• Adjust compile scripts
• move base files
• split up random stuff files (mainStyleSheet.css, ...)
• move 003-assets/CSS/
• move gui/css/
• move other files