fixed crash on mono palette
use palette for blink - much faster text write
fixed missing cursor in screen 1 with palette-blink
scrap feedback more often visible with palette-blink
removed screen global
surface0 -> canvas, cursor0 -> cursor
simplified and reordered check_screen
simplified do_flip
no more need to exclude composite artifacts from smooth scaling
found a place on the palette for scrap feedback colour
fixed all-blinking wide chars. Docstrings.
adjusted warning messages
typo caused missing background to chars
fixed flashing colour anmalies on clear screen and scrolling
screen border for pygame backend
added --append to PCBASIC.INI