* Enums can now be dynamically created in the _itemf callback, using RNA_enum_item(s)_add, RNA_enum_item_end. All places asking for enum items now need to potentially free the items. * This callback now also gets context, this was added specifically for operators. This doesn't fit design well at all, needed to do some ugly hacks, but can't find a good solution at the moment. * All enums must have a default list of items too, even with an _itemf callback, for docs and fallback in case there is no context. * Used by MESH_OT_merge, MESH_OT_select_similar, TFM_OT_select_orientation. * Also changes some operator properties that were enums to booleas (unselected, deselect), to make them consistent with other ops.