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).
hgweb: Serve raw non-binary files as text/plain
Previously these were served as application/octet-stream usually making
browsers download them as files though they can be displayed inline just
fine. This is useful to refer to e.g. /project/raw-file/tip/README.
allow committing a removed directory
fix
issue1089