[REVIEW 3-5-2] Fix for fdo#47406 and compatibility option to import right our older documents

[Fridrich Strba]

Hello, good people,

Between me and Thorsten (more Thorsten then me as usual), we fixed the
fdo#47406. We would love the distinguished readership to review and
cherry-pick for 3.5.2 the following two commits:

http://cgit.freedesktop.org/libreoffice/core/commit/?h=libreoffice-3-5&id=db3597cef07a0f659be5617d9148069c7fb4a5a8

and

http://cgit.freedesktop.org/libreoffice/core/commit/?h=libreoffice-3-5&id=b8fb2df5491937ccc7eb422544e25f18a6bc787c

Note that they are already in 3-5 branch and thus we need two brave
reviewers for the 3-5-2 branch.

Cheers

Fridrich