[MERGED PR] Makes Stowaway a latejoin role

[Glamurio]

With regards to issues with it being relegated to a latejoin job (like antag count at roundstart), why can't currently-latejoin-only jobs be made pickable on character selection? They could be hidden by a Display Other Jobs toggle button so they don't clutter job select, with a disclaimer that these jobs aren't garanteed to be available. If you chose one job that doesn't end up available the game can still fall back according to your other preferences.

Off-topic, but going out on a limb that admins are worried about enabling special jobs too much lest the majority of players plays special jobs rather than mainstay jobs. I personally don't think that's a problem, so long as most available special jobs are a variation of a mainstay (psychiatrist for doctor, for instance).