Improved readability of OUString concatanations. Also removed unused
OUStrings "sColor" and "sEntry" from the code.

Change-Id: Ie9792f499cd880be72229f8a8c71f05ff8e258b6
Reviewed-on: https://gerrit.libreoffice.org/28375Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>