Add Production.BuildTeamFromTemplate

Production.BuildTeamFromTemplate allows the production of teams from a
list of
actor types, assigning a function to that team once it is complete.

A 'template' in this case looks like this:
template = { {factory, {list of units to build using aforementioned factory}} }
e.g. template = { {barracks, {"e1", "e1", "e1", "e3", "e3"}} }

You can also build teams using multiple factories like this:
template = { {barracks, {"e3", "e3", "e3"}}, {war_factory, {"3tnk", "3tnk"}} }

Before using Production.BTFT you need to call
Production.EventHandlers.Setup once.

mods/common/lua/production.lua

@@ -1,4 +1,5 @@
 Production = { }
+Production.EventHandlers = { }
 
 Production.BuildWithSharedQueue = function(player, unit, amount)
 	Internal.BuildWithSharedQueue(player, unit, amount or 1)
@@ -8,6 +9,17 @@ Production.BuildWithPerFactoryQueue = function(factory, unit, amount)
 	Internal.BuildWithPerFactoryQueue(factory, unit, amount or 1)
 end
 
+Production.Build = function(factory, unit, amount)
+	if Actor.HasTrait(factory, "ProductionQueue") then
+		Production.BuildWithPerFactoryQueue(factory, unit, amount)
+	elseif Actor.HasTrait(factory, "Production") then
+		Production.SetPrimaryBuilding(factory)
+		Production.BuildWithSharedQueue(Actor.Owner(factory), unit, amount)
+	else
+		error("Production.Build: not a factory")
+	end
+end
+
 Production.SharedQueueIsBusy = function(player, category)
 	return Internal.SharedQueueIsBusy(player, category)
 end
@@ -29,3 +41,54 @@ Production.SetPrimaryBuilding = function(factory)
 		pb:SetPrimaryProducer(factory, true)
 	end
 end
+
+Production.BuildTeamFromTemplate = function(player, template, func)
+	local factories = { }
+	Utils.Do(template, function(t) table.insert(factories, t[1]) end)
+
+	if Utils.Any(factories, Actor.IsDead) then
+		return
+	end
+
+	if Utils.Any(factories, function(fact) return Production.EventHandlers[fact] end) then
+		OpenRA.RunAfterDelay(Utils.Seconds(10), function() Production.BuildTeamFromTemplate(player, template, func) end)
+		return
+	end
+
+	local team = Team.New({ })
+	local teamSize = 0
+	Utils.Do(template, function(t) teamSize = teamSize + #t[2] end)
+
+	local eventHandler = function(unit)
+		Team.Add(team, unit)
+
+		if #team.Actors >= teamSize then
+			func(team)
+			Utils.Do(factories, function(factory)
+				Production.EventHandlers[factory] = nil
+			end)
+		end
+	end
+
+	Utils.Do(factories, function(factory)
+		Production.EventHandlers[factory] = eventHandler
+	end)
+
+	Utils.Do(template, function(t)
+		Utils.Do(t[2], function(unit)
+			Production.Build(t[1], unit)
+		end)
+	end)
+end
+
+Production.EventHandlers.Setup = function(player)
+	Utils.Do(Actor.ActorsWithTrait("Production"), function(factory)
+		if Actor.Owner(factory) == player then
+			Actor.OnProduced(factory, function(fact, unit)
+				if Production.EventHandlers[fact] then
+					Production.EventHandlers[fact](unit)
+				end
+			end)
+		end
+	end)
+end