Move nasty cruft from make.rules' $(CUTCRUFT) here, mostly to clean up

make.rules.

Doc/tools/sgmlconv/fixgenents.sh

@@ -2,6 +2,9 @@
 #
 #  Script to fix general entities that got translated from the LaTeX as empty
 #  elements.  Mostly pretty bogus, but works like a charm!
+#
+#  Removes the leading XML PI that identifies the XML version, since most of
+#  the XML files are not used as top-level documents.
 
 if [ "$1" ]; then
     exec <"$1"
@@ -13,7 +16,7 @@ if [ "$1" ]; then
     shift 1
 fi
 
-sed '
+grep -v '^<?xml .*?>$$' | sed '
 s|<ABC/>|\&ABC;|g
 s|<ASCII/>|\&ASCII;|g
 s|<C/>|\&C;|g