Fix T39148: Image does not show while rendering

Own regression since partial buffer update refactor,
display buffer for exr tiles should happen in image
update callback.

This revision is to be merged to the final release.
Fix for possible (unlikely) uninitialized var use in BM_face_split
BMesh: minor changes for BM_face_split use
Fix for compilation error since previous fix for XCode
Fix T39151: Boolean modifier freeze

This re-applied patch from 25cbd13 which was lost at some point
since missing patchset in series.

This revision is to be back-ported to the final release.
Cmake: fix compile problem after own commit
Fix T39152: Blender crash when duplicate mesh with hooks and laplacian deform.

We can't simply dupalloc cache_system (LaplacianSystem), it has quite a few allocated data we'd need to dupalloc as well,
not to mention (nl) context... Much safer to just set it to NULL in new copy imho!

This commit is to be backported to 2.70 release!
Freestyle: Fix for a potential implementation error in the Python wrapper of the Nature class.
Code cleanup: cmake
Fix T39146: recent cycles CUDA regression in fix for T39114.

This commit is to be backported to the 2.70 release.
UI: Show edge draw options for duplis, it applied to their instances
OSX/GHOST: fix T39153, pls check on win minimized window load
Fix T39158: Help > Operator Cheat Sheet causes a python recursive loop.

Core issue exists since ages - the thing you get from bpy.types.YOUR_OT_operator is fuzzy, and may change,
due to the fact that both Operator and OperatorProperties share the same name...
Would be cool to get rid of this issue one day, but for now it's safer to use rna acessor...

This commit is to be backported to 2.70.
Fix own bug after HSL picker commit. HSV Cube based pickers missed HSV
buttons.
GHOST: cover now both win and osx case for T39153
Typos in last commit, sorry
Fix bug 1 of T39156: Deadlock while undoing paint operations on image
sequences.

This commit should be included in 2.70 release
Fix cycles texture interpolation mode closest constant offset on some devices
Fix T39156 part 2: Add support for image paint operations in undo
history operator (Ctrl + Alt + Z).

This will only show paint operations now while in an image paint mode.
The caveat is that user can delete previous paint operations too (even
on images not on the canvas currently) so it needs some care. This is
consistent with regular undo behaviour though.

Sculpting also suffers from lack of Undo history support, this will be
added in a separate commit.
Some corrections to previous commit. Undo stack could return 0 or return
global undo even if not set in preferences.