Add Keizer-Swiss mode.

[Dumuzy]

A playing mode which resembles swiss system, but with some of the Keizer specialties kept:

• A victory against anybody counts the same. 1 point. Like in Swiss.
• Colors are managed like in Keizer.
• Players that are not there can get fractions of points like in Keizer.
• Players which have games against resigned players get points like in Swiss.
• Principally, a player can play against another one twice, like in Keizer. This can be prevented completely by the tournament director by increasing the setting "# rounds before pairing repeat" beyond the number of rounds of the tournament.

[pascalprog]

A very good idea to invent a hybrid system between the Swiss system and the original Keizer system.

The strength of the Keizer system compared to the Swiss system are:

1) The possibility of being able to replay several times against the same opponent, which allows to imagine a tournament with an infinite number of rounds. This is interesting when the tournament has few players (for example to easily animate an internal tournament of a club, with a game evening every week for a whole year).

2) The system seeks to pair players of similar strength from the first round and not a strong player against a weak player as in the Swiss system. The fact of seeking to pair players of the same strength rather than strong vs weak makes the games more interesting to play, especially in the first rounds.