Ogre Update - Moving Mac to 64bit version

Hi all, we've done a quick update of Ogre today; the main change is that the game moves from 32 to 64 bit for Mac users, as Apple is doing a big change on the next OS towards 64 bit. (Note that if you want to keep the old 32bit version, you can still use that version. Full details can be found in the Steam Community post here!

Thanks all!