Fixed linking errors.
The foot-bot now gets added to and removed from the dynamics 2d engine.
Forced loading of all plugin libraries at startup of an experiment. Without that, the plugins can't be used.
Made a better check for presence or absence of the visualization in the XML file.
Added the missing "ENABLE_VTABLE" statement in the controllable and medium entities.
Minor change to space.cpp.
Added box and cylinder entities.
Minor change.
Added entity callback support into QTOpenGL visualization. User functions are still now supported.
A few changes to the foot-bot robot plugin.
Added simple test XML for box objects.