Error Levels

[rnugent3]

We need a consistent way of setting error levels - both for property rules/errors and for messages. The following are the available error levels:

public enum ErrorLevel : byte
    {
        Unassigned = 0X00,
        Info = 0x01,
        Minor = 0x02,
        Major = 0x04,
        Fatal = 0x20,
        Severe = 0x40,
    }

Unassigned or Info are the least severe, whereas severe is the most severe. @HenryGeorgist @Brennan1994 @rtle76 @codymccoy what do you think about this mapping:

• Unassigned: Let's do our best not to rely on unassigned error levels
• Info: Nothing is wrong or even potentially wrong. Things are working as expected.
• Minor: It is possible that something is wrong, but all computes will run successfully. E.g. monotonicity.
• Major: Something is wrong. The compute will run but the results will not make sense. E.g. weird uncertainty parameters, like a CSVR of 1000%.
• Fatal: Something is so wrong that the compute will fail. E.g. negative standard deviation.
• Severe: Apocalypse.

[rnugent3]

Should monotonicity be major or minor? If there is a big monotonicity problem, then major. If we're forcing just one or two coordinates, then I think it is minor.

In UPD - we have monotonicity checks. Let those monotonicity checks give out a major error while the stuff in PD give off a minor error? This way the non-monotonicity is communicated just once.