Put code in a better position
Remove zip files
Add compact mode to context editor. closes #41

I tested it some but not so thoroughly. If you find bugs let me know in the issue tracker.
Transfer dragging related code from ContextEditor to ContextMatrix

It conceptually fits much better into ContextMatrix
Transfer header renaming related code from ContextEditor to ContextMatrix

It conceptually fits much better into ContextMatrix
Extract utility code into Util
Extract utility code into Util
Improve ContextMatrix code organisation

Also paint dragged header cell darker.
Transfer ContextMatrix into its own file

ContextMatrix now is kind of reusable and deserves to be in its own class. In addition, the ContextEditor.java file just became too big and hard to navigate in.
Fix last behaviour oddities of the context editor

My baby is perfect now!