[freeciv-ai] Ferry dating agency.

[Gregory Berkolaiko <Gregory.Berkolaiko@xxxxxxxxxxxx>]

(I hope my email will not be classified as spam due to the subject).

This is about how ferries find their passengers and vice versa.
Several approaches are possible, for example:

1. Ferries do PF search which goes inland too.
2. Land units do PF search which goes into the seas.
3. Land units head for the nearest shore.  Ferries do PF search up to 
coastal tiles.
3a. As in previous, but unit head for the nearest port.
4. Ferries head for the nearest port.  Land units do PF search through 
their continent only.

Right now a dodgy version of 3 is implemented.  Ferries do their search 
alright, but whether land units will go anywhere depends on luck (see 
find_boat function).  This works fine if the land unit is on the shore in 
the first place, which is most of the time.

I am inclined to change to system 2.  Any comments?  Suggestions of help?

G.