Adapt to dmd 2.064 and some minor fixes

- Vector2f and Rect: no more unnecessary template ctors
- Font: correct miss alignment and reduce size from 20 to 16 byte
- TileMap: correct miss alignment and change ushort[2] to short[2] to
fit ShortRect.setPosition
- VertexArray: change type from size_t to uint (because of OpenGL
compatibility)
- VorbisFile: removed unused import thanks to
https://github.com/Dgame/DAT