off-by-1 fix for _seql on non-digit move sequences
add F12+ keys, who knew mac keyboard shift+f1=F13
add test for _seqlen
additional test; MBS + 0-254 char padding
add test case for _is_movement

caught \033#8, my favorite 'fill the screen' sequence. not that anyone would have noticed.
fix for \033c (reset) and \033#8 (fill the screen)