Adds accuracy modifier support

code/modules/projectiles/gun.dm

@@ -21,9 +21,10 @@
 	var/fire_sound_text = "gunshot"
 	var/recoil = 0		//screen shake
 	var/silenced = 0
+	var/accuracy = 0 //accuracy is measured in tiles. +1 accuracy means that everything is effectively one tile closer for the purpose of miss chance, -1 means the opposite. launchers are not supported, at the moment.
 
 	var/last_fired = 0
-
+	
 	//aiming system stuff
 	var/keep_aim = 1 	//1 for keep shooting until aim is lowered
 						//0 for one bullet after tarrget moves and aim is lowered