fixed bugs on on_piece_move

new function: mode.square_fall
new autocall: check_custom_flip

fixed vanilla black piece effect issue
added custom flip condition support

help fix the vanilla mode.turns issue

Fixed on_sq_init and on_card_init getting called multiple times

Updated mode.strike

updated sort_spawn in the manual

only check the name of functions now
fixed potential bugs
replaced old upd codes with loop

lowered healing sfx volume

healing can't make pieces have more hp than max hp anymore

traverse mods in correct order