improve text of reset button on „Players & Profiles“ screen
add new scoringSystem property to GoGameRules and to NewGameModel (#30)
expose scoringSystem property in the "New game" screen (#30)
configure the GTP engine according to the selected scoring system (#30)
rename GoScore property „territoryScoringEnabled“ to „scoringEnabled“ (#30)

also rename goScoreTerritoryScoring* notifications to goScoreScoring*.
this change is somewhat cosmetic, but necessary since we are about to
change GoScore to not only support territory scoring, but area scoring
as well.
implement area scoring in GoScore (#30)