add option to always pass use key through special lines like prboom-plus

[devinacker]

prboom-plus has an option to treat all special lines as having ML_PASSUSE set, which is needed for cchest2.wad MAP24 (and possibly other "Boom-compatible-but-not-quite" maps) to be completable. This adds that option, disabled by default.

Also attached a dumb test map as a more obvious/contrived example.
passusetest.zip

[ioan-chera]

Sorry, but I wouldn't add another comp_ option, we have too many already. Also this invites bad level design, kinda like a slippery slope.

I may look more into this if it can be isolated, though I'm also not much fond of wad hacks either (i.e. like ZDoom or occasionally Eternity, activating hidden compatibility flags based on loaded wad hash). Ultimately, if user only tested this on ZDoom, then it's a ZDoom map without all the features, and player can choose between playing it in ZDoom, or cheating/skipping it as buggy. We already have lots of vanilla wads too which are buggy and need cheating, so this is not new.

[Altazimuth]

I think this is a fair option to have, printz. Enough maps targeting Boom break thanks to only being tested in ZDoom with its non-default defaults. We may have too many comp_ options but this one feels necessary.