things to look at optimising:

	raycaster main loop:
	- 1/sin and 1/cos stuff in distance calc
		- replaced with pythagoras using GBA sqrt - much faster
		- look at 1/sin table and 1/sin and 1/cos functions?
			- done - not used for distances though - sqrt seems quicker
			
	- slice_height calculation (1/distance)
		- implemented a slice_height table for 0-500

	- tex_inc_low/tex_inc_high calculation
		- implemented a table for 0-1000

	- 1/tan in horizontal scan
		- 1/tan table/func?
			- done
