Texture tools robustness:
* Pressing x or y to scale overlay immediately presents visual feedback
instead of requiring mouse motion
* Hide the ovelay icon when stencil is active since you can't deactivate
then.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55907 954f8c5b-7b00-dc11-b283-0030488c597c