Mac: Read $PROG_DIR/../../.. when querying iwads and files

[Rachael]

This is something that I think would make cross-platform distribution of full games a lot easier.

For anyone who doesn't already know, Macintosh versions of programs have to exist inside of an "app bundle" which is simply a specialized folder which contains the program and icons and the resources for said program. This has the mega-advantage that you only have to drag a single icon into your Applications folder and you have fully installed the entire app - which is a huge convenience over Windows and Linux.

However, Windows and Linux do not work this way, and the files must either exist loosely or be packaged into a single file themselves. Not ideal for a GPL game.

For Steam, I have tried cd'ing to $PROG_DIR/../../.. using a special run script rather than the application itself, but for some reason that does not work in Mac OS 10.12 and higher or Mac OS 11. It only works in Mac OS 12.

(Of course if the problem is tighter security in 10.12> or 11, then obviously this won't work either, but adding this in would make it so I no longer need that script)

"Why not just put them inside the app bundle?" - this is not how Steam distribution works. If you want to take advantage of the separate depots for executables and data, so that you only have to upload the data once, you need it all in a single location. This would work just fine if you are okay with uploading 3 entire copies of your game to Steam, but I would prefer not to do that. >.>