Initial port of Jedi Outcast back to gcc/unix

Here are the initial parts to make Jedi Outcast compile and run.  Save games are not yet handled properly on amd64 due to some horrible pointer casts in the original code.

The multiplayer code is currently not ported, only single player.

Tested on OpenBSD (i386 and amd64) and linux (i386), I don't have a windows compile environment here but I've tried not to break windows while doing this.

Data from both the demo and the full game from steam seem to be compatible.