Implementation of fast interfaces for contexts in path from
ScXMLImport::CreateFastContext to ScXMLTableRowCellContext.
FastParser is enabled and duplicates are avoided at all
possible places.
OOoXML filters still need those legacy paths we removed,
so I had to temporarily map them to fast elements, which
would increase their load time, but hopefully it should
help us in the long run.

Change-Id: Ie997a9a8b72787da2356abc99ea2cd57c2e5b670
Reviewed-on: https://gerrit.libreoffice.org/28648Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>