Adding Direction Enum.  This should help in the areas we have non-constant strings being used in relation to the cardinal directions.
Added the next method to the coordinate class.  This leverages the Direction Enum.  I changed the player.bearing return type to Direction.
Added projectedPosition method in player.  This will return a coordinate of the next turn's position of the player.
Adding tests for player class and coordinate class.
Adding Fix for bug in directional logic.
Converted direction to enum syntax and specified Dart 1.8 as minimum sdk
updated cases to match enums
fix typo
Player testing playa!
Lower-case that biz
Merge pull request #4 from jonkirkman/game-loop-tangent

Direction enums & Player tests