Added skills Lightning, Potion, RadiusCommand and Throw, and cleaned up

Added skills Lightning, Potion, RadiusCommand and Throw, and cleaned up some code from previous changes. Also unintentionally pushed .classpath change, oops

New Skills:
- lightning radius:damage =0 1
- potion radius:type:duration:level =0 1
- radiuscmd radius:'kill $player' =0 1
- throw radius:horizontal_force:vertical_force =0 1