This adds arrows + home + end key navigation.

The grid is handled like a list. For convenience Left + Up
and Right + Down keys work in the same way.

Change-Id: I757184e5161f2c7ac9b241294a5edc304c882497
Reviewed-on: https://gerrit.libreoffice.org/72792
Tested-by: Jenkins
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>