Include mbf21demo.wad

[SirBofu]

We should put the MBF21 demo showcase .WAD in the repo for posterity and ease of access.

[XaserAcheron]

That WAD is a bit old, and technically incomplete -- it only shows off the mapping features. I have a newer version lying around that has a DEH feature showcase area, though it isn't quite comprehensive (much closer, though). I can scrounge that one up, though it may have a couple of rough parts still.

[EDIT] Oh welp, I totally forgot I made it public at some point -- repo's here: https://github.com/XaserAcheron/mbf21edit -- no tags/releases yet but it's a standard DoomMake project.

Maybe instead of holding on to that repo, I could transfer it over to the doom-cross-port-collab org instead, then we could make some release tags and link it. Probably better to not have me try and solo manage it, since my brain be what it do.

[electricbrass]

I was actually just thinking of suggesting we have a doommake project thats maintained alongside any further revisions to the spec. In fact a wad that was more than just showcasing things but was instead set up specifically for verifying proper implementation of features would be really nice. Ideally in a way thats clear without needing to compare against other ports as much as possible, and with demos included. Unfortunately OPTIONS would need a bunch of separate wads as long as we have no way to set those per-map...

[XaserAcheron]

The linked project could maybe be useful as a starting point, at least. I'll transfer it over shortly.

[EDIT] Is done. Hope it helps a bit!