added jbox2d libraries
created package for physics, added basic possibility for own jbox2d-tests (as described in their wiki)
only store last MAX_REC_SCREENSHOTS (currently 50) screenshots to avoid memory issues
updated .classpath
removed absolute pathes
created PhysicsSimulationAgent and place WorldObjects in the simulation (well kinda)
whatever
Merge pull request #5 from crisHH/platas_branch

Platas branch