Fixed insane MouseCursor definitions

This is a breaking change since some of the MouseCursor name changed,
but in the long run this makes a lot of sense!
Simplified little endian check
Added experimental Sprite3D class
Changed PerspectiveProjection constructor
Renamed PerspectiveProjection.perspectiveMatrix3D
Added comment for Sprite3D
Added Sprite3D offsets for all axis
Fixed 3D transformation calculation
Apply 3D transformation relative to pivot point
Less memory allocations in Sprite3D renderer
Simplified Matrix3D.prependTranslation
Avoid RenderState allocation in Sprite3D.render
Minor code beautification
Fixed 2D matrix with 3D matrix calculations
Changed perspective projection formula