transfer level exp and current exp not being different enough, which
limits the amount of natures possible. Could handle the 100&<=2 cases
the same way, but keep the branches for faster cases.
fix bad test cases
V### names weren't enjoyable to work with; use similar verbose style as
the program message strings.
updating the translation files with the remapped variable names shortly
remap list: https://pastebin.com/jybkVDAK
Checks.cs initially started out small, but over the years it has grown
to handle multiple types of checks. With all these checks next to
eachother, it's hard to see the overall groups. Splitting them up
(potentially further?) allows for more focused maintenance &
understanding.
Not sure if I'm happy with the overall bandaids used (checks no longer
done within LegalityAnalysis so variable repointing is excessively
used), but I'm happier the way it is now compared to the huge Checks.cs
