cp#1000025: Import casemaps from pptx.

(Ported from: 887bc4dd3e62fe6dd19dc9d1c3ba273a5b21b5ec
and 9dbcb79782d6a5b80c21a0c093537d18425b826f)

Change-Id: I211491e06273aedf5c8ddbd0ca3fc35f3d168aaa
Reviewed-on: https://gerrit.libreoffice.org/7848
Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Andras Timar <andras.timar@collabora.com>