Added Human driven strategy

Which is just driven by simple console input currently.

- Added a discard function which only discards the highest value card
in the player's hand.
- Added a HighestDiscardStrategy class.
- Replaced a few bare constants with constants from the Card class.
- Added information to each Card class so that it can inform the
Strategy classes whether it needs a target and/or a guess to function
properly.
- Added discard pile output to the game status function.
- Added a function to find a Player object by number to the Game class.