2017-06-22 Airplane bug and fix

Frontline Pioneers! Today some of you were affected by a bug that led to your airplanes behaving like marching troops/convoys. This is fixed know. To 'cure' the affected units you will have to do a little workaround, though:

1) find another (still flying) airplane

2) merge it with the broken one

3) give a new patrol command to both airplanes

This will fix the behavior of the first one and it will fly again (even if you split the two airplanes again).

Keep on testing and thanks for your effort!