Replace =~ with #matches?. #208.

Replace =~ with #matches?.  #208.

=~ made sense when we were passing it through to a regex, but we're no
longer doing that: TagMatcher looks at individual tags and returns a
value that *looks* like what you get out of #=~ but really isn't that
meaningful.  Probably a good idea to not subvert convention like this
and instead use a name with guessable intent.