Disabled data access in particle RNA.

Only the general attribute descriptions and state instance can be
accessed from plain bpy now. For detailed data read/write the bparticles
module has to be used.

This was forced by a change to collection iterators, which essentially
makes them unsuitable for anything other than ListBase and arrays
(state attributes and particle data in this case). It may be possible
to reeanble this later, but generally bparticles is the better approach.

Fixed a few small merge errors. Sorted libs are now defined in
macros.cmake.

Merge branch 'master' into particles_refactor

Conflicts:
source/blender/blenkernel/intern/object.c
source/blender/blenkernel/intern/rigidbody.c
source/blender/blenloader/intern/writefile.c
source/blender/python/intern/bpy_interface.c
source/creator/CMakeLists.txt

Fix for variable declaration after code (invalid C).

Fix for dupli type bit flags exceeding short range.

The nparticle dupli flag was using 1<<15, which gives issues with signed
short variables. Fortunately there are unused bits in the
Object.transflag, now reuse the deprecated OB_POWERTRACK flag for this.

Also replaced dupli context int type with short to avoid errors with
strict compiler flags.

Added missing support for quaternion attributes in the bparticles API.

Replaced the RBO_GET_MASS and RBO_GET_MARGIN macros with proper
functions.

There is really no reason to use macros for this sort of thing.

Moved build/apply functions for constraints into rigidbody_objects too.

This is only about object-based constraints. Bullet constraints can be
added for other future use cases too outside the objects code.

Moved functions for object component data management (RigidBodyObject
and RigidBodyCon) into rigidbody_objects.c as well.

Moved transform utility functions for objects into the rigidbody_objects
source file.

Renamed them a bit to make clear these are for objects only.

Separation of concerns: Moved functions for building object rigid bodies
and applying Bullet results to them into a dedicated file.

The same should happen for particles, shapes, constraints etc. later.

The purpose of this is to keep the main Bullet world API limited to
dealing with Bullet primarily and avoid fixating it on Object DNA data.

Sensible default value support for particle attributes. Some data types
(normal, color, quaternion, matrix) get common default values, others
are just 0 and have to be defined by the user if necessary.

Boilerplate RNA for the particle display settings.

Added default rotation attribute.

Basic dupli display for particles.

Conflicts:
source/blender/blenkernel/intern/anim.c

Add a dupli display method by default.

Fixed read/write code for particle display dupli lists and added a
modifier object walk callback (also used in readfile for generic
modifier lib_link).

A couple of small fixes for merge issues.

Use instanced object collision shapes for particles instead of plain
spheres. The "collision_shape" attribute is no longer needed, the shapes
can be retrieved from the instanced objects instead (which must be RBs
themselves).

Free dupli object lists correctly when freeing display structs.