Replaces yet more istypes with helpers (#20806)

* uses more istype helpers

* oranges is inefficient

code/modules/mining/equipment.dm

@@ -531,7 +531,7 @@
 /obj/item/weapon/twohanded/required/mining_hammer/afterattack(atom/target, mob/user, proximity_flag)
 	if(!proximity_flag && charged)//Mark a target, or mine a tile.
 		var/turf/proj_turf = get_turf(src)
-		if(!istype(proj_turf, /turf))
+		if(!isturf(proj_turf))
 			return
 		var/datum/gas_mixture/environment = proj_turf.return_air()
 		var/pressure = environment.return_pressure()

code/modules/mining/mine_turfs.dm

@@ -394,7 +394,7 @@
 
 	if (istype(P, /obj/item/weapon/pickaxe))
 		var/turf/T = user.loc
-		if (!( istype(T, /turf) ))
+		if (!isturf(T))
 			return
 
 		if(last_act+P.digspeed > world.time)//prevents message spam
@@ -553,7 +553,7 @@
 		digging_speed = P.digspeed
 	if (digging_speed)
 		var/turf/T = user.loc
-		if (!( istype(T, /turf) ))
+		if(!isturf(T))
 			return
 
 		if (dug)