Move player command

This adds a menu when the player chooses the move option. The menu shows the map and lists the possible places the player could move (or Enter to cancel). When the player chooses a location to move to, the Player.location instance variable is set to the Location object.

To test:
1. N for new game
2. A for add player
3. Enter player name
4. S to start game
5. M to move player