watercolor effect implemented basic. stamps still working on in this branch
added sailboat stamp from external source
undo implemented using CommandItem base class with multiple inheritance and QUndoCommand functionality
save and load functionality working on a basic level. Simply saving/loading the canvas, no serialization, etc.
added scaling factor for initial drawing of a stamp
cursor completed
Merge branch 'master' into hkuhn_watercolor_stamps
Merge branch 'master' into irene

Conflicts:
	canvas.cpp
	item.cpp
	mainwindow.cpp