Added SDL2_image and SDL2_ttf init and deinit
Added SDL2_image init to constructor
Fixed wrong way around definition of Sizei and Sizeu. What a stupid mistake...
Added DrawSubPart() and DrawTile() to interface
Added LoadFont() to interface.
Added CreateFromSurface(). Implemented DrawSubPart() and DrawTile(). Added source filename as member. Now initialized SDL2_image. Better error handling.
Implemented LoadFont()
Added Font2d interface
Implemented Font2d interface with Sdl2Font2d