Replace World::getConfig with World::getFloatConfig, World::getIntConfig, and World::getBoolConfig.

Also fix a warning from a previous commit.

--HG--
branch : trunk

src/server/game/Grids/ObjectGridLoader.cpp

@@ -264,7 +264,7 @@ ObjectGridUnloader::Visit(GridRefManager<T> &m)
     {
         T *obj = m.getFirst()->getSource();
         // if option set then object already saved at this moment
-        if (!sWorld.getConfig(CONFIG_SAVE_RESPAWN_TIME_IMMEDIATELY))
+        if (!sWorld.getBoolConfig(CONFIG_SAVE_RESPAWN_TIME_IMMEDIATELY))
             obj->SaveRespawnTime();
         ///- object will get delinked from the manager when deleted
         delete obj;