[[ ImageCenterRect ]] Implemented getter.
[[ ImageCenterRect ]] Started to integrate decompose_matrix so rotated nine-way stretch will work - not yet correct :(
[[ ImageCenterRect ]] Decomposition still not working.
Merge branch 'develop' into feature-center_rect

Conflicts:
	engine/src/graphicscontext.cpp
[[ ImageCenterRect ]] Got reasonable implementation of nine-way rendering working which takes into account semi-pixel coverage.
Merge branch 'feature-center_rect' into develop