Changes/fixes when constructing water structures.

[serVar161]

Changes/fixes when constructing water structures.

1) Ship Dock. Show the entire required construction space.

When building a ship dock, if it's placed incorrectly, you'll receive the messages "The main part of the dock must be in water." or "The end of the dock must be on land." Okay. Got it.
However, in some cases, you still won't be able to place it because the ship dock requires an additional 3.5 tiles of free space along its length.
After you place the dock, the construction area suddenly expands by those same 3.5 tiles, but when selecting the construction site, it's not visible, making it unclear "why can't I place it??"

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2) Watermill. Change the description and system messages when building it incorrectly.
"A watermill provides sufficien power for two machines, which can be built anywhere inside the mill. Note that the wheel if the mill must be submereged in wather, while the foundation of the mill must be built on land."

a) Change the description by replacing "water" with "river."
The description simply says "in water." But, as I understand it, it can only be built in a river.
Or "deep water" if the watermill can be built on anything other than a river.

b) Change the system messages when building watermill incorrectly. Like a ship's dock.
Currently, the same message always appears: "You cannot build that on this type of terrain." Even though the land is fine, the problem is the water.
Make it like the ship dock:
- If the problem is with the land part, it says "You cannot build the "mill entrance"* on this type of terrain."
- If the problem is with the water part, it says "The mill wheel must be in a "river" (or deep water)."
- if there might be issues with the middle part, I don't know but if so, report it separately.