all but egg exposed it; now, just make egg expose it and remove the unnecessary interface
we still need to Set generation for non-eggs/mgift, so have a separate Settable interface for internal purposes.
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
Closes#2040 , adds test cases:
invalid bulbasaur.wc3: hidden ability
invalid charmander.pcd: hidden ability
valid camerupt: gen3->4 unevolved mismatch
valid leafeon: pcd mismatch -> evolved now matching
should be much easier to maintain; methods are reused with less overall
nesting
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
