Blender Git Loki

Small cleanup.

- Remove unnecessary forward declarations
- Use MEM_callocN to initialize memory for new caches, would assert due
to OpenVDBCache.filename not being initialized.

Exporter: clip grids based on the density field to save on file size.

Patch by @lukastoenne.

Merge branch 'alembic' into gooseberry

Fix outdated stub factory class for pointcache when Alembic is disabled.

Disable collapse images option after operator ends.

Collapse image sequence feature now uses BLI_path_* functions to detect
filenames.

Fix stupid recent mistake

Merge branch 'master' into gooseberry

Conflicts:
source/blender/makesdna/DNA_object_types.h

Make clamping able to return to exact previous values.

Add an 'is_color' metadata to set an rgba socket for color grids

Load image sequence collapsing for sequencer

Very dirty feature that will have to be reimplemented when the new asset engine makes it into blender.

This commit tweaks the filebrowser to detect sequences of images that form parts of a movie. The
files need to be in the format <number>filelame.ext or <number>.filename.ext

There is a new option next to hidden file option that makes it so this collapsing takes place.

When collapsing is on, any movie files that have the same filename will be collapsed to the first
detected file in the sequence. Selecting that file will select all files in the sequence.

There is a shortcut in the sequence editor in the Add menu, "Image Sequence" that enables collapsing
by default. Unfortunately, selecting multiple movies will not add multiple sequences to the sequencer,
at least for now, but it should make it quite easier for people to quickly select the whole range of
images for a movie. Importing the image sequence into the sequencer will use placeholders, so any missing images
will display as black.

Merge branch 'master' into gooseberry

Conflicts:
intern/cycles/kernel/svm/svm.h

Merge branch 'master' into openvdb_smoke

Various cleanup.

Quick fix for data corruption happening when changing scene frame in
separate threads.

Patch by @lukastoenne.

Quick fix for openvdb::ArithmeticError being thrown on frame 1.

Issue is that the smoke simulator stores a zero'd object matrix on frame
1 which makes OpenVDB throw because the matrix is then non-affine.

Patch by @lukastoenne.

Quiet compile warning when WITH_OPENVDB is off.

Merge branch 'alembic' into gooseberry

Only use string properties from the cachelib for metadata.

Using ints and floats would require prefixing the Alembic metadata
keys, which becomes messy and ambiguous. Encoding other data types as
strings can be done on the python side as well.

Have to use IDP_ReplaceInGroup to overwrite ID properties that already
exist.