Deobfuscate, deduplicate and fix Corsica vs. Sardinia and Pyrenean Sierra, refs rP11266, rP12248.

Use vector algebra instead of adding one equation for each dimension everywhere, refs #4845.
Add common createPassage terrain helper function to unify straightPassageMaker and the modified copy PassMaker, refs #4805.

On Corsica vs Sardinia:

Comfort island shaping by
not hardcoding and not hiding magic numbers behind magic equations,
not specifying areas and deriving the radius from the disk area,
but always refer to newly introduced radius globals and compute the area using diskArea from rP20332.

Don't give some players 10% more map area and place all circular island parts at the same center location in the map corner.
Don't place trees and mines into passages.
Simplify and order numbers, increase fail fractions from 4 to 10.
Use mapCenter getter from refs #4854.