INT 33,3 - Get Mouse Position and Button Status

	AX = 03


	on return:
	CX = horizontal (X) position  (0..639)
	DX = vertical (Y) position  (0..199)
	BX = button status:

		|F-8|7|6|5|4|3|2|1|0|  Button Status
		  |  | | | | | | | `---- left button (1 = pressed)
		  |  | | | | | | `----- right button (1 = pressed)
		  `------------------- unused


	- values returned in CX, DX are the same regardless of video mode