added type xrule (from sextension.ML);
removed old 'extend';
removed added syn_ext_const_names, syn_ext_trfuns (now in syn_ext.ML);
various minor changes;
#! /bin/sh
#rm-logfiles: remove useless files from subdirectories
rm log */make*.log */make*.log.gz
rm */test
rm */.*.thy.ML
rm */ex/.*.thy.ML
rm HOL/Subst/.*.thy.ML