Feature: Exclude lines that match a regex

[reitzig]

As a writer of AsciiDoc files, I want to be able to limit line length overall but exclude lines I can not shorten, e.g. links with long URLs.

Problem: AsciiDoc supports only line comments, not trailing comments (cf. asciidoctor/asciidoctor#991).

Proposal: Support excluding lines (in certain files) if they match a regular expression. Extend the exclude list to support

Example usage (for this use case):

.ecrc

{
    "exclude": [
        {
            "files": ["*.adoc"],
            "lines": ["^\\s*link:"]
        }
    ]
}

(not married to the syntax; I'd image one would like to migrate from string elements like "*.lock" to { files: ["*.lock"] } eventually?)

I would have to test w.r.t. performance impact; but since this is a strictly opt-in feature, the trade-off would be the users'.