add ParticleGroupTycoon for all the particle related global updates #121
move split along longest axis to helper header + fix it =) #121
split particle groups along the longest axis #121
split down particles only #121
register new groups created while splitting after splitting is done #121
fix copy construction of down groups #121
remove empty down groups #121
ignore useless linker warning for RelWithDebInfo
fix bounding box if updatePhysics is called before updateVisuals on ParticleGroup #121
implement particle group merge #121
Merge branch 'master' into split_121

Conflicts:
	libelemate/world.cpp
fix physx access violation error. #121
fix for linux. #121
move velocity readdata flag activation into ParticleGroup constructor. #121
Merge pull request #129 from lanice/split_121

Particle group split&merge 121