db: calculate number of matches and opponents for a player
db: calculate number of matches and opponents for a player

Add a helper function that calculates the number of
matches and the number of different opponents that
a player has played.

Signed-off-by: Ilija Hadzic <47a09d4a4430975766160361f65fc72633be50b6@gmail.com>

ihadzic/jim,ihadzic/jim,ihadzic/jim