The game previously did this dumb thing where it lumped in all its
settings with its file that tracked your records and unlocks,
`unlock.vvv`. It wasn't really an issue, until 2.3 came along and added
a few settings, suddenly making a problem where 2.3 settings would be
reset by chance if you decided to touch 2.2.
The solution to this is to move all settings to a new file,
`settings.vvv`. However, for compatibility with 2.2, settings will still
be written to `unlock.vvv`.
The game will prioritize reading from `settings.vvv` instead of
`unlock.vvv`, so if there's a setting that's missing from `unlock.vvv`,
no worries there. But if `settings.vvv` is missing, then it'll read
settings from `unlock.vvv`. As well, if `unlock.vvv` is missing, then
`settings.vvv` will be read from instead (I explicitly tested for this,
and found that I had to write special code to handle this case,
otherwise the game would overwrite the existing `settings.vvv` before
reading from it; kids, make sure to always test your code!).
Closes#373 fully.
These XML functions will be useful for de-duplicating copy-pasted XML
handling code, while also making it so elements will get updated in
place instead of being thrown out and starting from scratch every time a
file is saved.