First step towards fixing some issues noted by Vincent. We record in the

First step towards fixing some issues noted by Vincent. We record in the
Buffer whether we are exporting or not, rather than rely upon isClone(),
which could be adapted to other purposes. And, of course, someone might
choose locally to disable cloning....

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@34999 a592a061-630c-0410-9148-cb99ea01b6c8