this exposes 3 unused private members, detete them.
reorder some initialization to match declaration order.
remove a broken and redundant member initialization
and destruction in xfindex.cxx
(starts loop at 1 and default ctor/dtor do the same)
simplify default ctor in xfframe.cxx

Change-Id: Iaada8849e030d494a9bc7f7b0c3f8f1da3828290
Reviewed-on: https://gerrit.libreoffice.org/24466Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>