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
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
tip 3:a49829c4fc11
t1 0:f7b1eb17ad24