EasyGamma v0.01
because some time i want change the game gamma......

gamma available value between 0 and 2.0
1.0 = regular gamma
above 0 = brighter
below 2.0 = darker

Param Examples:
	+	default the gamma increase 0.02
	-0.1	the gamma decrease 0.1
	0.5	set the gamma to 0.5
if param is null will reset the gamma.