I added the speed/lift caps based on a ship's class. The maximum values are
tuned assuming a full crew of rank 5-7 sailors/speed/lift magi, hence will not
be exceeded for most ships. And, as I mentioned before, there are other
benefits to having a higher level crew.

In the process, I realized that the old speed cap would easily be reached by
an elite crew. I looked over the code, and I believe that there are no issues,
so I raised the absolute cap as well, max ship speed is now about 25% faster
than it used to be. Let me know if anything bugs, however.

Keep in mind that autopilot is heavily dependent on your navigator's level,
and even a maxed out nav will not be able to pilot a ship on autopilot as fast
as it can go on flat out cruise/autocruise.

Melemkor