Use ToTempSummon() in a case instead of a C style cast.

Use correct Unit::GetCreature() instead of Unit::GetUnit() with casting the object to Creature pointer.
Remove some usless casts.
Fix a possible crash in pyrewood_ambushAI.

TODO: Remove ugly cast macros(like CAST_PLR(), CAST_CRE()) from scripts and use the correct ToX() functions(like ToPlayer(), ToCreature()).

--HG--
branch : trunk

src/scripts/northrend/ulduar/ulduar/boss_algalon.cpp

@@ -333,7 +333,7 @@ struct mob_collapsing_starAI : public ScriptedAI
 {
     mob_collapsing_starAI(Creature *pCreature) : ScriptedAI(pCreature)
     {
-        pInstance = (ScriptedInstance*)pCreature->GetInstanceData();
+        pInstance = pCreature->GetInstanceData();
     }
 
     ScriptedInstance* pInstance;

src/scripts/northrend/ulduar/ulduar/ulduar_teleporter.cpp

@@ -23,7 +23,7 @@ The teleporter appears to be active and stable.
 
 bool GoHello_ulduar_teleporter( Player *pPlayer, GameObject *pGO )
 {
-    ScriptedInstance *pInstance = (ScriptedInstance *) pGO->GetInstanceData();
+    ScriptedInstance *pInstance = pGO->GetInstanceData();
     if(!pInstance) return true;
 
     pPlayer->ADD_GOSSIP_ITEM(0, "Teleport to the Expedition Base Camp", GOSSIP_SENDER_MAIN, BASE_CAMP);