Texture stencil:

Robustness: Avoid translating the stencil outside the active area. Helps
to avoid losing the stencil somewhere in bitspace.

Usability: Take image repeat mapping and scaling into account when
fitting stencil aspect. Togglable by operator properties.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56042 954f8c5b-7b00-dc11-b283-0030488c597c