Deleted abstract class PhysicalObject. It requires discussion.
Pointmass is now a PhysicalObject
getOrganismCount is in all environments. Test case set up for TinyCar
FIXED GRID (removeEmpties wasn't working)
fixed inverted turn direction in tinycar
added a 'keep_alive' option to testenvironment, which constantly feeds the organisms
Sigh, git.
Some trivial changes to Grid, VeryTinyCar, and SimpleCircleOrganism. Test environment runs smoothly with 200 simpleCircleOrganisms on the field.
Added sensitivity and strength constants for senses and actions, respectively.
VeryTinyCar.collide() written. Doesn't work because Environment.getNearbyAsym() is broken.

Also various comment cleanups