add glfw_getKey() to lua
store element type in ParticleGroup, create PSA instance explicitly

- static object instances are difficult to handle correctly, as you can't know when there ctor will be called.
reorder folder structure
move terrain actor init to terrain generator
define sources and shaders in separate CMakeLists.txt
Merge branch 'project_reordering' into particleCollision_92

Conflicts:
	CMakeLists.txt
	src/rendering/drawable.cpp
	src/rendering/renderer.cpp
	src/ui/eventhandler.cpp
	src/ui/hand.cpp
	src/world.cpp
implement basic bbox based collision check #92