removed obsolete theorems;
handle generic XML markup as well (plain <markup> instead of <... class=markup>);
misc tuning/update according to Pure/Generic/markup.ML;
By chapter:
chapters 1 and 2, maybe 3: Peter White
chapters 6, 7 and 8: David von Oheim
chapter 6, maybe 8: Gerwin Klein
chapters 3, maybe 4: Tanja Vos
chapters 1-3 at least: Stefano Bistarelli