Fix T38503: crash in non-threadsafe VBO free code during render.
Fix T38521: skin modifier crash with zero radius vertices.
Fix T36979: wrong render of textured mesh lights with multiple importance sampling.
Fix T38370: Ubuntu 14.04 opencolorio segfaults blender on parsing colormanagement/config.ocio

Ubuntu hack: add a --libyaml-cpp-ver parameter, to try to force installing a given version of this lib...
(only for DEB-like distro, I dare hope Trusty (!) is the only affected distro.
Not happy at all to have such things here, this is actually an Ubuntu bug, but will have to live with it I guess.
Add Tabs for Movie Clip Editor

Based on the patch from Sebastian Koenig, discussed with Jonathan Williamson

  https://developer.blender.org/T38172

Also removed redundant modes from clip editor.

Reviewers: brecht, carter2422

Reviewed By: carter2422

CC: sebastian_k, carter2422

Differential Revision: https://developer.blender.org/D293
Fix for button comparisons ignoring rna-index
Code cleanup: move old->new button search into ui_but_find_old
UI: avoid O(n2) for old button lookups since both lists are almost always aligned
Bevel Modifier: fix bug T37916, bad result after mirror modifier.

Bevel needs the vertex normals to be correct and they are not
normally recalculated after a previous modifier, like mirror.
Adding 'dependsOnNormals' -> returns true to modifier info
for Bevel fixes the problem.
Fix T38538: repeat history menu show operators that can't be repeated.
Texture Nodes: "At" distortion node was missing from the add menu.
ListBase API: add utility api funcs for clearing and checking empty
some systems didnt define NULL
Cycles Standalone: Exit when no xml file can be found.
Cycles Standalone: Expose Shader settings in the xml api.
UI: butstore API to generalize button storage for modal handlers
UI: split ui_button_execute_do into begin/end
UI: multi-drag number button editing

clicking and dragging down edits multiple number buttons at once. (patch D270)
Fix collada compile ( kudos ti ideasman )
T38482: Fixed the Crashing. If the same UV Layer is referenced multiple times, then the last imported data set for this UV Layer wins.