Fix T41784, Re-enabling transparent shadows in Cycles doesn't work correctly
Followup for last commit, we can break the loop, once we have a match.
Fix T41785: The combination of movie-distortion and lens-distortion leads to artifacts
Fix wrong area of interest for movie undistortion
Workaround for strict flags and release build compilation

@campbellbarton, it's really helpful to have strict flags enabled
for release builds as well -- especially when you're working in areas
which are heavily using least squares solvers.

For now made it so blender compiles, but it could be better solution here.
Tweaks to setup trackign scene in order to fix usability issues

Patch by Sebastian Koenig
Tracking: Fix wrong behavior of refining with previous frame matching
Fix related to T41780, sequencer weirdness with alpha under effect

Fix alpha under equation according to porter-duff and user docs that
state that effect should invert he order of channels and reduce to alpha
over when factor is 1.0.

BTW, we don't really expose any factor here...lost feature from 2.49?
Fix T41780

Expose sliders for alpha over/under/overdrop
Now it's apparent that the effects work as explained in the manual.
Cleanup & remove redundant check
Fix T41788: bmesh.utils.loop_separate, face_vert_separate() always return None
OSX: Fix cmake3 usage
Fix scons leaving partially generated files when aborting
Fix T41800: Freestyle + Cycles panoramic camera not compatible, renders are incorrect.
Fix T41811: unreachable code in wm_keymap.c

There was also an issue with passing sl->spacetype here, for some reason...
typo correction in the python API
Cleanup & typo in assignment
Correct last commit
Sculpt: check mask is present before reading
Correct invalid sizeof in memset use