Removed old unused nparticle modifier code.
Particle display type for duplis.
Moved the particle display list from the modifier into the psys itself.
This makes the modifier more easily replaceable later on and allows
more detailed management of the particle object settings (in particular
dupli flags).
Automatically set the object transflag for nparticle duplis, like
current particles (but actual code is in nparticle to stay out of object
code as much as possible).
Single display 'add' function, is easier to provide as API method.
Add a dupli display method by default.
Boilerplate RNA for the particle display settings.
Free dupli object lists correctly when freeing display structs.
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).
Basic dupli display for particles.
Added default rotation attribute.
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.
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).