improve/fix/repair harbours/landing-stages

[viktor]

boats on sea water should not be able to dock to a landing stage or undock from a landing stag into the sea,
boats on lake water should not be able to dock to a coaster harbour or undock from a coaster harbour to the sea

there is a strage bug in the game, you can be in a boat in the sea, if you are close to the coast and there is a lake wit cities on it and they have landing stages, you can if it's close enough dock to the landing stage, of a city that has no sea access, from the sea. this should be impossible and cen be nothing other than 'magic' when it happens in game

you can still bet between lakes and seas by docking to the shore first as always and have your full options of undocking.