Replace pandoc-based md-to-man conversion with a custom python script.

Hopefully this will appease the people who can't install pandoc on MacOS.

Documentation/md-to-man.do

@@ -1,5 +1,6 @@
-if pandoc </dev/null 2>/dev/null; then
-	echo 'pandoc -s -r markdown -w man -o $3 $1.md.tmp'
+redo-ifchange md2man.py
+if ./md2man.py </dev/null >/dev/null 2>/dev/null; then
+	echo './md2man.py $1.md.tmp'
 else
 	(IFS=:; for DIR in $PATH; do redo-ifcreate "$DIR/pandoc"; done)
 	echo "Warning: pandoc not installed; can't generate manpages." >&2