This adds the ability to save and load vector layers. This review request is here mostly because of the changes made to KisShapeLayer.h for whom I am not sure how dangerous they could be.
There's still update issues and I am not sure what to do with the X and Y values that MyPaint DOES write to ora, as does GIMP, but only show up in the examples in the spec, and not the actual spec text itself(there's no explanation of them).
EDIT: This patch doesn't change strings, which might be relevant in how serious it is.