EntityItem::setSimulationState() now public
add EntitySimulation and SimpleEntitySimulation
EntitySimulation takes EntityItem* rather than ID
EntityServer gets a simuation
EntityCollisionSystem moves to interface

and interface connects EntityCollision system to EntityTree
EntityTreeHeadlessViewer gets a simulation
merge upstream/master into andrew/thermonuclear
add entities to simulation after unpacking
moving EntityCollisionSystem back to entities lib
OctreeServer::createTree() is now protected
merge upstream/master into andrew/thermonuclear
Merge pull request #3870 from AndrewMeadows/thermonuclear

pull entity simulation out of EntityTree