Examples:
	sheety cat -i "sheety/tests/machete_idle.png" -s 256x256 -i "sheety/tests/machete_swing01.png" -s 256x256 -d "packed columns"
	SAME AS
	sheety cat -i "sheety/tests/machete_idle.png" -s 256 -i "sheety/tests/machete_swing01.png" -s 256 -d "packed columns"
	SAME AS
	sheety cat -S 256 -i "sheety/tests/machete_idle.png" -i "sheety/tests/machete_swing01.png" -d "packed columns"

	sheety cat -i "sheety/tests/machete_idle.png" -s 2-1 -i "sheety/tests/machete_swing01.png" -s 4-4 -d "columns 4"

Commands:
	cat to concatenate

	slc to slice and keep one or more items
 
	del to delete one or more items

	rev to reverse a sprite sheet