Trade IV: Fixing the Seaways

I had a Big Problem with the way the seaways were generated, so I haven't included them in the trade network yet. But this is a shame. So I will fix it.

Mostly, it's good. But occasionally, weird stuff like this happens (the route marked in red). The error happens during the "refueling stops" portion of the code. First, a seaway is found between two cities of appropriate size and infrastructure. These are the anchor points. However, these routes are quite long - I limit it to search within 50 hexes, or around a month at sea. That's not impossible, but for a regular trade route is pretty tough. You want the ability to stop at a friendly port and resupply. So the code will then search along that route for nearby cities. They must have more than 1000 people, but can be much too small to originate a route of their own. So the code will split up the original, long route into manageable chunks.

However, I was getting this weird error where the splitting was rejoining everything back together incorrectly. That should be fixed now, and I can add these into the main trade network. As it is, everything is pretty isolated without access to other continents.

I would also like to determine a "piracy index" based on the frequency of ships passing through a given hex. This is gameable information: stuff that's not just pure numbers for my own enjoyment. Players can make decisions (to pirate, defend, or take the long way) based on this gameable information.