Spectators

Finally add a working spectator mod(e) for staff. I've made two PRs for CTF V2 to fix the encountered issues which were approved by a bunch of people and they were for some incomprehensible reason still refused to being merged. This should IMO include:

• visual invisibility, ofc not only but especially when joining the game
• not being pointable
• a /watch command that doesn't get the spectator uncovered when the watched player does /m
• no join or leave messages
• do not show full privs list of spectators to normal players
• do not show spectators in /team, /who or /status
• exclude spectators from the match summary or rankings if possible
• anything else?
  Conclusio: Spectators should be completely inexistant to normal players
  Maybe you can use this as some kind of checklist @olliy1or as I've seen you've been working on a new PR already.

Start by reviewing the existing spectator work in PR #24 and compare it with this issue's checklist. Verify the requested behavior for invisibility, /watch, messages, privilege visibility, team and status listings, and rankings. Done means spectators are completely hidden from normal players across the listed views.