Initial commit, vehicle overmap tracking.

Add enable/disable gps entry to vehicle control menus.
Implement basic tracking that works for up to 3 overmap tiles away,
after that the vehicle note will follow the player around.
Another thing that still needs to be done is to save the gps status of the vehicles, im guessing i will need to dive into gamesave.cpp for that.

Here is a screenshot, click to expand.
<a href='http://s9.postimg.org/ckdki2tn3/2013_11_09_100028_1044x564_scrot.png'><img src='http://s9.postimg.org/oz0ciel57/2013_11_09_100028_1044x564_scrot.jpg' border='0' alt="screenie" /></a>