Git Code Merge Request #8: Added possibility to scroll map with arrows (merged)

Hello,

Added support for scrolling the map with arrow keys. Holding the key continues to scroll.

Known issue: moving a mouse while holding a key will reset the movement, due to zeroing the step structure. To fix it a separation of keyboard and mouse scrolling would be needed with completely separate variables. However the current approach seems to work quite well. At this point I did not want to restructure the whole thing, as I dont know if you will accept big changes.

I hope you like the change.

BR,
yanss