while at it let's avoid creating 16 OUString objects per run from
the same 8 constants.. and let's avoid parsing the source 4 times
when 1 time suffice... and of course use OUStrinBuffer to construct
the result rather than creating and recreating OUString over and over.

Change-Id: I74fdb8b51bab91a0883db65bc8c5d0e8606e2da4
Reviewed-on: https://gerrit.libreoffice.org/2326Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>
Tested-by: Norbert Thiebaud <nthiebaud@gmail.com>