Handle difference in water level handling between Carnivores, and later titles

[Ithamar]

In the first carnivores, the heightmap specifies water level (i.e. top surface), and the watermap has the "water floor" heights for water tiles.
In Carnivores 2 and IceAge, the heightmap has water floor heights, and the watermap specifies an index into the waters table in which the water level is specified.

When loading Carnivores maps, if map is version 1, correct heightmap and dynamically create the water table and a corrected watermap.