Point submodules to their latest release branch

Version bump to 2.80 final release

Linux: update appdata description

Doxygen: update version number

Fix T67777: Linked rig crashes Blender 2.8 RC3 on File|New.

Sync back between proxy armature pose and linked one was not properly
clearing the posebone runtime data, ending up with shared memory between
both (direct cause of reported crash), and probably some other nasty
issues.

While this crash is not critical in itself, I would suggest to add this
fix to 2.80 branch, as it is super-safe and simple, and is probably
fixing some other un-reported issues?

Point submodules to their latest release branch

Splash: show Release Candidate 3.

Bevel modifier: let it work on wire edges when vertex_only.

GPencil: Fix wrong material when apply Opacity, Hue or Tint modifier

When apply the modifier a new material is created, but it was assigned wrongly. The problem was the index was base 0 already, so subtract 1, got a wrong value.

Fix T67040: Undo crashes after renaming

Correct fix that doesn't cause T67217.

Temporarily removing the excluded undo step broke memfile-undo
since freeing the undo steps needs to access other steps in
the list to merge shared chunks, see: memfile_undosys_step_free.

Pass the exclude step as an argument instead.

CMake: Fix WITH_CODEC_SNDFILE detection

D5296 by @frispete

Fix T67033 EEVEE: Random Flickering Materials

This was a read after free error. This only fix the undefined behavior.
The result is still not correct in certain cases (see T67226).

We want to include this for 2.80

Fix T67196: bevel bad at a 3-edge bevel.

The test for whether or not this was a "pipe" neglected to use
fabsf() around a dot result.

Fix T67450: Crash undoing edit-mode lattice resolution

Fix assert in some cases when using DataTransfer modifier for custom normals.

Reported by @sybren on IRC, thanks.

Should be safe for 2.80.

Incompatible usage of the Collada transparency value

Some external tools seem to have issues with the definition
of Collada <transparency> - a float value in range (0,1).
However it is possible to use the <transparent> color as a container
for the <transparency> value. This seems to be a more reliable
method to export transparency values from Blender PBSDF Shaders.

The relevant documentation is in the collada 1.14 reference manual,
page 7-5 about the usage of transparent and transparency.

This fix makes export and import of the <transparency>
and <transparent> values more convenient and more reliable.

Reviewers: brecht, jesterking

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D5305

Fix T67191: Redo fails for 3D text operations

Fix missing subversion bump for 2.80 release.

We need a final subversion bump before release in case there are
remaining 'unversioned' code in our versionning callbacks...

Should have been done before first RC actually. ;)

To be ported to 2.80 release branch.

GPencil: Fix showing wrong material in brush panel with pinning

The options of the material are from object material not pinned material.

If the brush is pinned, the material must be the brush material and not the object material.

Revert "Fix T67040: Undo crashes after renaming"

This reverts commit c635663e4a8169f68010b9234fa60f17ad03d7cb. This is causing
crashes with sculpt mode and object mode switching.

Fixes T67217.