Movement cost errata

[DM B]

Some of the rugged terrain types are too costly to move through on roads/trackless.

The most important change is Med. Mnt. It costs 4 MP with roads, 6 with trackless (this is important when using the passes across the Seamist mounains. I.e. it cost 4MP to move from Nentril to Seamist or from Brosien to Seamist, not 6. It would cost 6 MPs from Vanilen to Marilen since there is no road there.