SCUMM HE: Use FilesystemNode::openForReading() instead of 'new Common::File' (didn't cover all instances, though)

Files:
modified: /scummvm/trunk/engines/scumm/he/resource_he.cpp (try)
modified: /scummvm/trunk/engines/scumm/he/resource_he.h (try)
modified: /scummvm/trunk/engines/scumm/he/script_v60he.cpp (try)