Cover VBL Addition

[ColdAnkles]

Identify the Bug or Feature request

Adds Cover VBL
closes #3732

Description of the Change

Adds cover VBL to available vision options.

Tokens outside cover cannot see into it - effectively identical to wall.
Tokens inside cover see out of it - effectively nonexistent.

Possible Drawbacks

Limited use? Unwanted? Complicates colours of VBL view.

Documentation Notes

The Hero Cannot See into Cover

The Troll in Cover, is unaffected, and can see the Hero outside.

Release Notes

• Added Cover VBL

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This change is 

[ColdAnkles]

This is a more complicated contribution than my first, so while I think its acceptable, I've got it in draft to allow for some commentary/feedback first.

[thelsing]

So this is basically a one may mirror? If so it works like hill-vbl but also supports lines. Maybe it could be foldet into it?
The question is how do you see wich side you can see through from.
I think draft-PRs are only necessary if you don't want the PR merged yet. If you think it could be merged just use a normal PR. IMO people will be more likely to look at "real" PRs.

[ColdAnkles]

More like pit-opposite. Pits can be seen into from outside, but can't be seen out of.
This you can't see into from outside, but can see out of.

[ColdAnkles]

Sometimes I really struggle with git and merging upstream changes back into my fork -.-

[kwvanderlinde]

Took this for a spin, there's one edge case that is not working as I would expect: a token in cover will have its vision blocked by the opposite side of an enclosed ocean (hole):

Compare with the case where the "hole" is not completely enclosed, then vision is not obstructed at all:

I would expect the first case to also not block vision either.