Added Image::getImagePart
Image now uses topleft positioning.

Also renamed a few functions.

These changes may break the Terrain module, but I'm not sure that one's currently used/developed.
Changed the Image::fill interface

It uses a color now, not 4 ints defining a color.
Merge pull request #280 from CIB/cleanup

Image updates
Fixed XY scaling in the 2d editor transform gizmo