VSE: skip non image/movie w/ proxy dir storage

This would use uninitialized filename variable,
looked into supporting this however generating proxies currently only
works for movies.

Depsgraph: Fix crash using --debug-depsgraph and --debug-depsgraph-no-threads

Was accessing past the array boundaries.

Should be safe for 2.79a.

Fix T53032: Image sequence works bad with Displace modifier

We shouldn't mix image pool acuisition with and without user provided,
the fact that internally image.c uses last frame from Image datablock
confuses the logic.

Blender 2.79a: Update submodules hash for addons

Blender 2.79a: Prepare for release

Enter release state and make spacing to "a" more sane.

There is still at least one fix we want to get in, before declaring we are
ready for release.

Minor change to last commit

Keep mode checks simple, nest other checks in their body.

Fix T54075: Align Objects fails w/ empty mesh

Fix T54072: Crash splitting edges

Cleanup: Python context access

Avoid access from bpy when it's already declared.

Fix T53958: Sequencer zoom 1:1 fails

Fix T50630: Fluid fails on win32 w/ unicode paths

Allow overriding gzip open w/ elbeem.

Fix: msvc build error with bli_fileops.h

bli_fileops.h was using uint64_t without including the proper header.

issue triggered by rBb0af44fa4d7a2e134b315c49a4fbdf573f781004

Docs: invoke_search_popup uses bl_property

Also add code example in docs.

Fix navmesh creation w/ multiple objects

D2976 by @dertom

Fix T53986: Crash saving during sculpt stroke

Also remove unused struct member.

Fix part of T53080: don't use current scene world for icon previews.

This can be very slow if it contains a big texture, and it's not
necessarily setup in a useful way anyway, and materials can be used
in multiple scenes.

Fix (unreported) crash when duplicating a FileBrowser window in preview draw mode.

We did not clear preview or smoothscroll timers pointers in copy code...

Fix missing group duplicated by hair in render

Was happening when viewport visibility on the particle system is disabled.
This became an issue after c45afcf, but the actual issue goes a bit deeper
and the following aspects were involved:

- Relations builder for particle system was ignoring particle system if
it's visibility is not enabled for viewport. This is something what
shouldn't have been done -- depsgraph relations are supposed to be the
same no matter if it's viewport or render.

- Relation builder was only dealing with duplication set to object, but
was ignoring group duplication.

This is NOT a regression since 2.79, but a regression since 2.79a-rc1.

Fix T53686: VSE Render crash when zooming timeline.

Epic fail from recent 'security' fixes (rBe04d7c49dca9). ;)

To be backported to 2.79a!

Fix T53962: Cycles OpenCL compile error in some scenes.

This part of 212a8d9e needed to be ported over for 2ca933f to work.