reagent holder rework (#6903)

- reagents are now singletons
- most of reagent holder datums are refactored.

code/modules/organs/external/external.dm

@@ -805,7 +805,7 @@ Note that amputating the affected organ does in fact remove the infection from t
 			if(!(W.can_autoheal() || (bicardose && inaprovaline) || myeldose))	//bicaridine and inaprovaline stop internal wounds from growing bigger with time, unless it is so small that it is already healing
 				W.open_wound(0.1)
 
-			owner.vessel.remove_reagent("blood", W.damage/40) //line should possibly be moved to handle_blood, so all the bleeding stuff is in one place.
+			owner.erase_blood(W.damage / 40)
 			if(prob(1))
 				owner.custom_pain("You feel a stabbing pain in your [name]!", 50)
 
@@ -1170,7 +1170,7 @@ Note that amputating the affected organ does in fact remove the infection from t
 
 	if(company)
 		model = company
-		var/datum/robolimb/R = GLOB.all_robolimbs[company]
+		var/datum/robolimb/R = GLOB.all_robolimbs[isnum(company) ? GLOB.all_robolimbs[company] : company]
 		if(!R || (species && (species.name in R.species_cannot_use)))
 			R = GLOB.basic_robolimb
 		if(R)

code/modules/organs/external/wound.dm

@@ -19,7 +19,7 @@
 
 	if((damage > 5 || damage + burn_dam >= 15) && type == WOUND_TYPE_BURN && (robotic < ORGAN_ROBOT) && !(species.species_flags & NO_BLOOD))
 		var/fluid_loss = 0.4 * (damage/(owner.getMaxHealth() - owner.getMinHealth())) * owner.species.blood_volume*(1 - owner.species.blood_level_fatal)
-		owner.remove_blood(fluid_loss)
+		owner.erase_blood(fluid_loss)
 
 	// first check whether we can widen an existing wound
 	if(length(wounds) > 0 && prob(max(50+(wound_tally-1)*10,90)))