* Small optimization to multires based on profiling data; calculation of edge boudndaries is now cached along with multires mapping data to improve the performance of the catmull-clark code.
* Removed an unneeded call to create the temporary data when loading files.
* Moved the multires vertex data from struct MultiresLevel to struct Multires. There's no longer any reason to store data seperately for each level; it was just taking up extra memory.
* Incremented the subversion to 2 and adjusted do_versions to correctly load older files.
* Refactored the multires update process (which handles propagating changes to other levels)
Fixed bug #6153, Blender Crash during rendering (internal) with object selected in edit mode.
* Added a render parameter to several of multires's functions. If render==true, multires won't push data onto the undo stack, and regular Mesh data is always used (as opposed to EditMesh data.)
Fixed bug #5756, Rendering artifacts when MRM is not set to maximum
Several changes were made:
* Added function multires_level_n to get the nth level from a multires mesh
* Removed the changes I made some time ago to init_render_mesh for multires meshes. Previously it was making a full copy of the mesh object in order to be able to apply deformations to the Pin level and propagate them to the Render level.
* Added two functions to DerivedMesh.c, multires_render_pin and multires_render_final. These two functions work together in the mesh_create_derived_*_render functions to apply all modifiers to the Pin level, then create the DerivedMesh from the Render level, and lastly restore the mesh to its original (undeformed) state.
* Added a check in multires_del_lower and multires_del_higher to ensure that level indices are properly clipped to the actual range of available levels.
Changes to CustomData:
Some functions would only return the current active layer, added extra variants that take an index to select the level (modeled after CustomData_get_layer_n.)
Still todo:
* UVs are being interpolated linearly, should probably offer Catmull-Clark subdivision like Subsurf modifier.
* Vertex Colors still don't support multiple customdata layers.
* Editing UV data on levels other than 1 should be disabled in the interface (same for weights)
