sub-/superscripts do not work

A patch for fo-body.xslt that makes sub-/superscripts (, ) work: I just replaced the baseline-shift property by vertical-align. According to the fop implementations page ( http://xml.apache.org/fop/compliance.html ), the vertical-align property is just a shorthand for baseline-shift, however, vertical-align works while baseline-shift doesn't ... (I got that from a recent thread on the fop-users list: http://mail-archives.apache.org/mod_mbox/xmlgraphics-fop-users/200508.mbox/%3c42EE0504.60201@tzi.de%3e )

The patch also reinserts some commented part that should work now after MPPDF-39 is fixed.