Alternative approach to troops sailing the 7 seas - Needs finetuning

[Hyronymus]

I thought about how to change the transporting of troops in galleys/galleons/transports whatsoever. If you look at how troops are airlifted once airports become available it's quite easy to think of a similar approach for sailing units.

With the availabilty of harbors you can order all land units to relocate to any other city within your empire that also has a port. The speed at which units are relocated can differ, mainly depending on having research marine technologies. Some illustrative numbers:

• with Mapmaking a unit takes 3 turns to move over a 30 tile distance
• with Seafaring a unit takes 2 turns to move over a 30 tile distance
• with Navigation a unit takes 1 turn to move over a 30 tile distance

Other requirements to move units between ports could be similar to the requirements currently in Civ3 for trade between ports (no enemy between the only direct harbor link, only sea tiles between the harbors).

There is one problem however: how to attack an enemy on a continent (island) where you have no cities? With my suggestion you can only do that with early marine assault units and only the Scandinavians have those in Civ3. Or perhaps you can still build transports for this kind of warfare?