Added sphere emitter
Added satellite emitter
Added cloth emitter
Added noop emitter
Added bounding box culling modifier
Added geometry collide modifier
Added global gravity modifier
Added pulsar gravity modifier
Added spring renderer
Refactored multi threaded particle physics into worker.cpp
Refactored global particle system method into it's own class
First simple integration with the (old) entity system
Improvements in billboard and cube renderers
Added some test cases