Avoid slightly-expensive QueryInterface() calls

Add CEntityHandle which wraps an entity_id_t and also has a pointer to a
per-entity array of IComponents. QueryInterface/CmpPtr on a handle just
involve a couple of pointer dereferences instead of a map lookup.

This requires sizeof(void*) per registered interface type per entity,
which is currently ~0.5KB per entity, which shouldn't be a problem.

This was SVN commit r13825.

source/simulation2/system/ComponentManagerSerialization.cpp

@@ -260,6 +260,7 @@ bool CComponentManager::DeserializeState(std::istream& stream)
 		CStdDeserializer deserializer(m_ScriptInterface, stream);
 
 		ResetState();
+		InitSystemEntity();
 
 		std::string rng;
 		deserializer.StringASCII("rng", rng, 0, 32);
@@ -292,7 +293,7 @@ bool CComponentManager::DeserializeState(std::istream& stream)
 			{
 				entity_id_t ent;
 				deserializer.NumberU32_Unbounded("entity id", ent);
-				IComponent* component = ConstructComponent(ent, ctid);
+				IComponent* component = ConstructComponent(LookupEntityHandle(ent, true), ctid);
 				if (!component)
 					return false;