#250 Landspies assault mobility use inconsistent

[Markus Armbruster]

When you assault with spies only, the spies try to
sneak ashore. Those who make it don't use any mobility.

However, if it's your own sector, mobility goes negative.

Whether sneaking ashore should cost mobility is
debatable, but reinforcing your own sector should cost
no more mobility than sneaking ashore.

[Markus Armbruster]

Fixed in commit 9f851c9, v4.4.0. Spies sneaking ashore use mobility and hit mines exactly like they do when reinforcing your own sector.