Various improvements to config code

[mfdorst]

• Make error messages more informative
• Add doc comments
• Make generate_config() private
• Reorder code so that public stuff comes first
• Fix typo

[HackedOS]

We were actually thinking of moving away from RON to a more user-friendly custom config, this might be an opportunity

[mfdorst]

Oh awesome, I was gonna ask if I could do that. I was thinking TOML, is that what you had in mind?

[mfdorst]

I'm also considering storing the default config as TOML or whatever we go with so that we don't have to write out the default config in rust, serialize it, then immediately de-serialize it the way we're doing now.

[mfdorst]

As per our discord discussion, TOML is off the table for this PR.

[eepy-goddess]

I hope we don't pick yaml :p

[mfdorst]

When I say TOML is off the table I mean this PR is done, I am not implementing a config language change at this time.