Add "incidence" fields for every nonfatal RFC incompliance

[ydahhrk]

So people can turn off these validations in a pinch, assuming the consequences are understood.

Several incidences are already defined, but it sucks that I'm adding them in a reactive manner. They tend to become available only after the window of time in which they would have been helpful.

Obviously, the default action of all new incidences should be error.

Branched off #96.

[lukastribus]

Hello,

considering this particular case only affects the AWS PP, I'm not sure that we should implement a workaround.

Afaik once the root cause is definitely fixed, rpki-client will also implement the check.

[ydahhrk]

That's ok; this feature is intended for future problems, and I'm not planning to prioritize it too much.

Since the project's development resumed in full a couple weeks ago, I'm going to be busy with the other bugs for a while.