* Wrap most user editable data in DNA_mesh_types.h and DNA_meshdata_types.h. Still needs to be improved in some areas though, especially how to deal with data layers (expose per element or as array, or both?), and data in face corners (bmesh type data structures are more logical here). Tweaks to RNA defining to make some cases easier: * Added range callback function for int/float. * Added 'skip' callback for listbase and array iterators to skip items in the collection. * Extra error print when calling wrong define_property_*_sdna functions. * Also made button code respect non_editable flag, is quick change though, need to add support for properly graying out etc.