to use Premake 3.1 (slightly modified - see next commit), and to
properly support VS2005. Should still be compatible with GCC, though
there may be differences I haven't noticed.
Removed option to build ScEd (because it won't work anyway).
This was SVN commit r3782.
Premake: allow slight separation of files' locations on disk vs in the
project tree.
Atlas: require fewer include directories.
This was SVN commit r2956.
