Fixing compilation (name of module Richprinter) I partially feel
responsible about.
Removing "destruct" test not yet working.
Fixing bugs #3723 and #3787 (reinitialization of camlp5 empty levels)
by hopefully computing the right position where to reinit an empty
level. Also removing obsolete comment.
Test for bug #3723 and #3787 on reinitialization of empty camlp4/5 levels.