Add files required to print callouts in html format.
- Previously, when you html files were produced, there wasn't any
image path nor image files for callouts. As consequence, callouts
weren't printed as expected. This update adds the SVGZ files and the
render.conf file needed to produce callouts PNG images. This update
also changes the related Xsl files to set the correct path of
callout images. Now, callout images are printed as expected in html
documents, produced from render module.