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/game/objects/items/policetape.dm

@@ -164,7 +164,7 @@ var/list/tape_roll_applications = list()
 	breaktape(W, user)
 
 /obj/item/tape/attack_hand(mob/user as mob)
-	if (user.a_intent == "help" && src.allowed(user))
+	if (user.a_intent == I_HELP && src.allowed(user))
 		user.show_viewers("\blue [user] lifts [src], allowing passage.")
 		src.density = 0
 		spawn(200)
@@ -176,7 +176,7 @@ var/list/tape_roll_applications = list()
 	breaktape(/obj/item/weapon/wirecutters,user)
 
 /obj/item/tape/proc/breaktape(obj/item/weapon/W as obj, mob/user as mob)
-	if(user.a_intent == "help" && ((!can_puncture(W) && src.allowed(user))))
+	if(user.a_intent == I_HELP && ((!can_puncture(W) && src.allowed(user))))
 		user << "You can't break the [src] with that!"
 		return
 	user.show_viewers("\blue [user] breaks the [src]!")

code/game/objects/items/weapons/defib.dm

@@ -320,7 +320,7 @@
 		user << "<span class='notice'>The instructions on [defib] don't mention how to revive that...</span>"
 		return
 	else
-		if(user.a_intent == "harm" && !defib.safety)
+		if(user.a_intent == I_HARM && !defib.safety)
 			busy = 1
 			H.visible_message("<span class='danger'>[user] has touched [H.name] with [src]!</span>", \
 					"<span class='userdanger'>[user] has touched [H.name] with [src]!</span>")
@@ -435,7 +435,7 @@
 		user << "<span class='notice'>This unit is only designed to work on humanoid lifeforms.</span>"
 		return
 	else
-		if(user.a_intent == "harm"  && !safety)
+		if(user.a_intent == I_HARM  && !safety)
 			busy = 1
 			H.visible_message("<span class='danger'>[user] has touched [H.name] with [src]!</span>", \
 					"<span class='userdanger'>[user] has touched [H.name] with [src]!</span>")

code/game/objects/items/weapons/handcuffs.dm

@@ -63,7 +63,7 @@ var/last_chew = 0
 	var/mob/living/carbon/human/H = A
 	if (!H.handcuffed)
 		return
-	if (H.a_intent != "harm")
+	if (H.a_intent != I_HARM)
 		return
 	if (H.zone_sel.selecting != "mouth")
 		return

code/game/objects/items/weapons/kitchen.dm

@@ -40,7 +40,7 @@
 	if(!istype(M))
 		return ..()
 
-	if(user.a_intent != "help")
+	if(user.a_intent != I_HELP)
 		if(user.zone_sel.selecting == "head" || user.zone_sel.selecting == "eyes")
 			if((CLUMSY in user.mutations) && prob(50))
 				M = user

code/game/objects/items/weapons/stunbaton.dm

@@ -117,7 +117,7 @@
 
 	var/mob/living/L = M
 
-	if(user.a_intent != "harm")
+	if(user.a_intent != I_HARM)
 		if(status)
 			user.do_attack_animation(L)
 			baton_stun(L, user)

code/game/objects/items/weapons/swords_axes_etc.dm

@@ -126,7 +126,7 @@
 			return
 		if(!isliving(target))
 			return
-		if (user.a_intent == "harm")
+		if (user.a_intent == I_HARM)
 			if(!..()) return
 			if(!isrobot(target)) return
 		else

code/game/objects/items/weapons/tools.dm

@@ -83,7 +83,7 @@
 	return
 
 /obj/item/weapon/screwdriver/attack(mob/living/carbon/M as mob, mob/living/carbon/user as mob)
-	if(!istype(M) || user.a_intent == "help")
+	if(!istype(M) || user.a_intent == I_HELP)
 		return ..()
 	if(user.zone_sel.selecting != "eyes" && user.zone_sel.selecting != "head")
 		return ..()
@@ -475,7 +475,7 @@
 
 		if (!S)
 			return
-		if(!(S.status & ORGAN_ROBOT) || user.a_intent != "help" || S.open == 2)
+		if(!(S.status & ORGAN_ROBOT) || user.a_intent != I_HELP || S.open == 2)
 			return ..()
 
 		if(S.brute_dam)