change API cs_close() to take pointer to handle as argument. this lets us invalidate the closed handle
fix a bug in cs_close(): improper check on handle value
python: update following the change to cs_close() API in the core
python: fix the leftover cs_close()
simplify cs_close() when freeing @printer_info, making it future proof for future arch
add some more comments regarding invalidating @handle of cs_close()