overhaul the rating and matchmaking system

[domino14]

• Fix all bot ratings (from Beginner to BestBot):
  900, 1200, 1500, 1800, 2000, 2200
  Ratings for bots are immutable. Can probably still use the Glicko rating formula but give the bots a rating volatility of zero if that makes sense. Can add 100 (?) pts or so for every speed level (classic uses the above ratings, rapid has 100 pts more, blitz 200, ultra-blitz 300). For super-fast games though BestBot might have less of an advantage than HastyBot so maybe ultra-blitz BestBot ratings would match Hasty's?

Determine the above ratings with a slightly more scientific system, based on how often the bots beat each other and the application of the Glicko formula

• Start all users at a 500 rating
• Have a filter in the seek for "provisional" players, allowing users to avoid playing provisional players.
• Increase the rating seek range
• Optional. Re-rate everyone as if this had been the rating system from the start. May be too difficult.