DotSceneLoader - fix compilation w/o Terrain, fix crash on parse error
DotSceneLoader - fix compilation w/o Terrain, fix crash on parse error

also report what went wrong on error
OGRECave/ogre,OGRECave/ogre,OGRECave/ogre,OGRECave/ogre,paroj/ogre,paroj/ogre,OGRECave/ogre,paroj/ogre,paroj/ogre,paroj/ogre