Scrolling the Viewport automatically

[Martin]

As of now the Steam supported version of CeasarIA seems to have no mouse scrolling feature, and it is required to press both mouse buttons to move the viewport.

Provide an auto scrolling feature for easier navigation.

[Jason Dishong]

used to be in there. i like the click and drag better but when you have a building ready to build you really want to scroll.

[dalerank]

autoscrolling work in fullscreen, in windowmode it hamper play