Switch the license to be LGPLv2/later, with small parts still remaining as GPLv2/later, by agreement of major contributors

Add server-side enforcement of the 'fast' privilege; also fix client checking 'fly' instead of 'fast'

The huge item definition and item namespace unification patch (itemdef), see http://c55.me/minetest/wiki/doku.php?id=changes:itemdef

Make dungeon masters though and make oerkkis disappear when they get to you (because hitting them doesn't work for some unknown reason)