NAME:
	ogif
 PURPOSE:
       sets device to z_buffer to allow plot to be made into gif later
 CALLING SEQUENCE:
	ogif,size=size
 OPTIONAL INPUT PARAMETERS:
       size: 	image size:
                       0: big (default) (600x600)
                       1: medium (400x400)
                       2: small (200x200)
			3: landscape (900x600)
			4: (600x700)
 OUTPUT: any subsequent plot graphic output will be send to a z_buffer
 MODIFICATION HISTORY
	Feb 94 - Written by A. Refregier
	Oct 2000 - Modified by S. Aigrain

(See /home/xmmssc/soft/idl/pro/misc_graphics/ogif.pro)