* User interface uses this as a tooltip when NULL or "" is given.
* Python doc generation includes this description
* Python defined ops take the description as an argument.
* NULL check to image_ops.c, was crashing on exit when there was an image open.
* Finished DNA_lamp_types.h, DNA_world_types.h and DNA_sound_types.h.
* Renamed "parent" struct property to "nested", and also remaining "from"
usage to "base".
* Added a NEVER_NULL subtype for pointers and use it for all properties
that apply.
* Make sure all structs have a description, and fix any other DOC_BROKEN
descriptions, also many other naming consistency improvements.
This is used for generating docs so a nested RNA struct such as MaterialRaytraceTransparency are listed under Material rather then in the global struct list)
These RNA structs are used for grouping properties and don't correspond to a C structure.
* errors in python called operators are raised as errors
* Python defined operators errors are reported as errors (not full traceback yet)
* added BKE_reports_string, same as BKE_reports_print but it returns a string rather then printing it.
* WM_operator_name_call optionally takes an initialized report struct
