by using for-range loops
+ use returned iterator by erase method
+ avoid some iterators calculus by using plain loop

Change-Id: I196a52c3c7d0e2705d5ab0e3ea06bd4a4b83bb67
Reviewed-on: https://gerrit.libreoffice.org/48805Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>