Various small fixes

[UncleVasya]

• [ ] Dota bot:
  • [x] !pd command should count votes;
  • [ ] don't let players join wrong team slot;
  • [ ] add !flip command;
  • [x] clear invites list when full queue becomes not full;
  • [x] don't send invites to players who are already in lobby;

  • [ ] people say bot spam pings them if they are not in dota;

• [x] Discord bot:
  • [x] add !recent command to show recent matches;
  • [x] show N recent status message instead of one;
  • [x] don't remove messages in queues channel if they edited less than 5 min ago;
  • [x] let 4500 MMR players vote on elite queue;

[UncleVasya]

Done.

!flip will do only if somebody asks for it.