commit (head): rest of 8918

clear undo buffer on "Purge all revisions" after asking the user for
confirmation.

(Purging all revisions involves some opetations that currently cannot be
undone (removal of the revisons table), and leaving the undo buffer in
place creates potentially unstable situations).

Tomas

Checking in xad_Document.cpp;
Checking in xad_Document.h;
Checking in xap_String_Id.h;
Checking in ap_EditMethods.cpp;
Received on Tue May 10 11:08:27 2005