highlight: only pygmentize for HTML mimetypes
For non-html mimetypes it doesn't make much sense. This also fixes the
issue that highlight unconditionally adds a <link/> tag for its CSS to
the template's header (which is pointless in text/plain output).
adding a
abort: journal already exists - run hg recover!
rolling back interrupted transaction
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions