format:<bank 1>,<starting screen 1> [<bank 2>,<starting screen 2>] ... if (level width - starting screen 2 - 1 <= 1 : there's no bank change)
examples:	50,03 52,0a
					54,05
52,0b
52,04 50,0a
56,05 57,0a
52,02 53,0b
50,03 52,0a
50,06
52,02 50,05
56,08
56,07 57,0b
53,06 52,09
50,0a 58,0c
53,05 50,09
52,05 50,0b
58,09
58,0a
57,06
5a,05
56,05 57,07
52,0c
50,06 58,0b