mainly by using for-range loops
but also by simplifying some simple algo

Change-Id: If04cd78e62f80f9575e24f3d50ff1e427454da79
Reviewed-on: https://gerrit.libreoffice.org/51019Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>