Added CampaignMap and MapLevel classes to the game code.

CampaignMap generates the map every level and passes it down
to the MapLevel class to render and set up player interaction.

Both classes are still a work in progress.
Added a tutorial map to the game. The map is loaded from an XML file and
will be static, except for road denominations.
Forgot to add XML tutorial map.
Game now displays fraction values near each road segment.
The car is back! Still needs a new coat of paint.
Vehicle can now move across the canvas when pressing WASD keys.
This is merely for debugging and testing purposes.
Vehicle stops at a hardcoded node.
Removing XML file that was checked in incorrectly.
Vehicle can now move across edges, but only one at a time.