* ignore SCALEn if CRYST1 is 1x1x1 or invalid
* new/refactored API functions for accessing coordinates and maps as numpy arrays
* new API function: cmd.set_state_order
* Session file (PSE) support for callback objects
* fix/silence many compiler warnings
* fix bg_rgb_top/bg_rgb_bottom side effects
* revert "fix setting surface_circumscribe"
* delete some obsolete files