Consider adding classifications to the lint list

[rmhrisk]

Right now each lint has a severity and a citation, it would be useful if the lints also had a classification, for example:

• Extended Validation Errors
• Validation Errors
• Encoding Errors

This would allow the tools that utilize zlint to quickly filter through the issues to get to the most pressing things within that classification.

[srdavidson]

I agree this would be useful - as issues in these buckets typically differ in resulting from a "process problem" and "technology problem".