[BUG] Sealink MV "Horsa" ferry mail hold wrong constraints.

[DrSuperGood]

The Sealink MV "Horsa" ferry is capable of sailing on Large River type ways. However the mail holds of it are not. Since it requires at least 1 mail hold to be functional this means that it technically cannot sail on Large Rivers.

The mail holds should share the same way constraints as the main ship. Most of them do, just this one seems to be an outlier.

[Spenk009]

I see the issue. Pull request here.

[jamespetts]

Thank you both for this: fix applied. That is most helpful.