[Proxy Alias] DNS name escaping

[bemasc]

It occurred to me that there is another context where the problem of escaping arbitrary DNS names has been solved: RFC 4501. That solution looks similar to this one (backslash-escaping of dots, then percent-encoding of everything) but not identical. For example, commas appear to be allowed, so the separator would have to be a semicolon.

It might be nice to avoid inventing another way to escape DNS names.