Normally -replies means that messages from and to the matching user are "ignored",
for the HILIGHTS level only messages to the matching user are "ignored" - if you
want to stop hilights for messages from the matching user too you need to create
a second ignore.

irssi has no ability to hide lines just because they triggered a hilight so the
above doesn't change anything other than the expected function of -replies when
stopping hilights.

This adds some small overhead to all ignore checking since it has to check that
either replies isn't enabled or that a level other than HILIGHTS is being checked.

If it's not obvious ignoring HILIGHTS from a user will only stop it hilighting
the line, it won't hide the line.

WARNING: when using -replies irssi completely ignores -pattern and -except, it also
won't check that for another ignore with -except set.

You can't use this with -except in the way you'd expect to be able to - it won't
not ignore a line just because it would have hilighted, the HILIGHTS level will
ONLY match when it's deciding if the line should hilight or not.