Units stuck while spamclicking

[bb]

Spamclicking a unit to go to the other side of an obstruction, doesn't move the unit. The problem here is that we don't know the actual path yet when we start to move. For the first turn we just try to move in the correct direcion, which can be wrong. Hence we try turning there too, which wastes some time, and thus we move slower/not at all.

Unsure what we need to do. Disallow spamclicking? Don't update the moverequest when its the same, i.e., don't compute a new path?

Reported by borg at ​phab:rP24415