Replace magic intent words with defines, grab fixes

This commit does the following:
 - Replaces all instances of magic intent words, like "harm" and
 "help" with defines, I_HELP, I_DISARM, I_GRAB, I_HARM

 - Fixes a few manual grab instances left over in attack_alien, they
 will now used grabbedby()

code/modules/mining/equipment_locker.dm

@@ -31,7 +31,7 @@
 	component_parts += new /obj/item/device/assembly/igniter(null)
 	component_parts += new /obj/item/weapon/stock_parts/console_screen(null)
 	RefreshParts()
-	
+
 /obj/machinery/mineral/ore_redemption/upgraded/New()
 	..()
 	component_parts = list()
@@ -604,7 +604,7 @@
 	stop_automated_movement_when_pulled = 1
 	mouse_opacity = 1
 	faction = list("neutral")
-	a_intent = "harm"
+	a_intent = I_HARM
 	min_oxy = 0
 	max_oxy = 0
 	min_tox = 0
@@ -668,7 +668,7 @@
 	SetCollectBehavior()
 
 /mob/living/simple_animal/hostile/mining_drone/attack_hand(mob/living/carbon/human/M)
-	if(M.a_intent == "help")
+	if(M.a_intent == I_HELP)
 		switch(search_objects)
 			if(0)
 				SetCollectBehavior()