add inventory shaders
add PlayerInventory
 add texture for inventory
implement inventory
inventory number
implement inventory number
fix wrong order of triangle of texture
fix crash in draw inventory. If the items is empty, we don't try to render anything.
remove the inventory container during the test
Merge branch 'collision' of github.com:LukasKalbertodt/cg-14 into collision

Conflicts:
	game/Player.hpp
change from gl_FragColor to out