backend.py docstrings, pylint fixes
pylint fixes
moved pen_was_down and stick_was_fired statuses into state
cwd should persist on resume
handle BASIC events in run.py to avoid complicated dependencies; they're only handled between events anyway.
Moved on_event into backend
disable events, macros and sound during SHELL
moved read_chars, get_char into backend
graphics.py var.arrays -> state.basic_state.arrays
handle --font option in backend_pygame
moved palette handling into backend
moved screen handling into backend (1 unsolved palette anomaly)