Move selected tile with arrow buttons in mapgen

[TheNewTeddy]

When generating a map, or picking a site for a colony, allow the selected tile to move with arrow picks, or, WASD.

This will help sticklers like me who want to get that perfect tile and click on ~200 before settling on one. We can find an area we like and just go up and down and left and right all over searching for that perfect tile without tiring our poor little mouse clickers.