Fix many syntax/type errors, style issues

    * Indent FUDGEDiceSet with tabs instead of spaces
    * Add a return type to Coin.roll()
    * Remove return types from constructors in my subclasses
    * super() doesn't work like it does in Python. Remove its misuse.
    * DiceSet is abstract, can't instantiate it
    * Use typing rules for DiceCache.add()
    * Add the new keyword places in DiceSet, GameMasterDice
    * Declare variables in DiceSet.getDiceSet(String)
    * Standard and FUDGE dice sets now extend DiceSet