[Feature Request] Robust configuration options

[Xaeroxe]

Support for configuration via a "breaking.toml" file where users can opt in to checks which may be too subtle for most usage.

It may also be useful to be able to add an attribute to a structure indicating the size of the structure is part of the public API and changes to that size must be noted. Similar to clippy attributes, I don't expect this attribute to change compilation output.

[o0Ignition0o]

Ooohh this seems like a super useful idea, like when someone adds an enum variant that ends up being huge in contrast to the others!

A first approach would be a "pedantic" mode or something, I'd be happy to work on that once we got the basics working!