Revert "Add kill assists (#755)" (#781)

This reverts commit 49f4e6fd47.

mods/pvp/anticoward/init.lua

@@ -153,7 +153,6 @@ minetest.register_globalstep(function(dtime)
 
 				if player then
 					player:hud_remove(potential_cowards[k].hud or 0)
-					ctf.clear_assists(k)
 				end
 
 				potential_cowards[k] = nil

mods/pvp/hpregen/init.lua

@@ -16,10 +16,8 @@ local function regen_all()
 			local newhp = oldhp + hpregen.amount
 			if newhp > player:get_properties().hp_max then
 				newhp = player:get_properties().hp_max
-				ctf.clear_assists(player:get_player_name())
 			end
 			if oldhp ~= newhp then
-				ctf.add_heal_assist(player:get_player_name(), hpregen.amount)
 				player:set_hp(newhp)
 			end
 		end

mods/pvp/medkits/init.lua

@@ -117,7 +117,6 @@ minetest.register_globalstep(function(dtime)
 			if pstat then
 				local hp = player:get_hp()
 				if hp < pstat.regen_max then
-					ctf.add_heal_assist(name, regen_step)
 					player:set_hp(math.min(hp + regen_step, pstat.regen_max))
 				else
 					stop_healing(player)