Blender Git Loki

Simplified cache item path description, based on plain ID blocks with
subtype/index.

This omits possible instancing and recursion by dupli groups, but since
the data of instances is always the same in Blender at this point, there
is little need to take them into account for caching.

At some point in the future it may become desirable to store full dupli
hierarchies in the cache, but it doesn't make sense to try to design a
fully-fledged path descriptor for this hypothetical case now.

Define a collection of "object_caches" in the CacheLibrary RNA for
iterating over all objects eligible for caching in the group.

This allows for nested dupligroup instances as well. All objects that
are instantiated at least once by any group can be included in the
respective cache, but get represented only once because the cached data
is the same anyway.

`New` operator for adding cache libraries.

Conflicts:
release/scripts/startup/bl_ui/properties_physics_common.py
source/blender/blenkernel/BKE_pointcache.h
source/blender/blenkernel/intern/pointcache.c
source/blender/editors/physics/physics_ops.c
source/blender/editors/physics/physics_pointcache.c

Draw some UI buttons for all the current cache item types.

Group pointer property for cache libraries to associate them with an
object group.

This is somewhat experimental, eventually we may want to link to Objects
instead, or allow multiple cache targets for the same cache, etc.

Fix for remaining PointCache references in the alembic code.

Now, for the time being, uses a simple relative "//blendcache/" folder
path again. This will be adressed later.

PointCache modifier to act as a terminator in modifier stacks.

When writing DerivedMesh data, the modifier result at the point of the
modifier will be used for writing to the cache. If this modifier is not
used the derivedFinal mesh is used instead.

Cache API for export/import of Blender data to/from Alembic files.

The pointcache API is designed to keep the general concept of caching
separate from the concrete Alembic implementation. Other types of file
export/import would be possible, e.g. for OpenVDB data.

Initial Alembic library integration for Blender.

Adds Alembic as a dependency and build support in cmake and scons.

Also extends the install_deps.sh script with a temporary installation
procedure for the Alembic libraries. This is still very hackish and
needs to be improved.