Blender Git Loki

[Coder API's]: Added a "generic unique name-finding function".

Basically, this is based on the behaviour of the unique_constraint_name (or equivilant) functions, which have traditionally been duplicated everytime a new datatype needed this.

Currently, this is in use for the following things:
* Constraints
* Action/Bone Groups
* Local Action Markers / PoseLib poses

Usage Notes:
* The file in which this is to be used should include the standard header file <stddef.h>. This defines the offsetof() macro, which should be used to find the relative location of the "name" member of the structs
* This function is only designed for names of up to 128 chars in length (Most names are at most 32. TimeMarkers are 64). If a longer string needs to be handled, the function will need to be modified accordingly.
* defname is the default name that should be used in case one hasn't been specified already