This is a combination of 2 commits.

Pass ScColumnsRange::Iterator as const&

Specifically for each operator==() call two temporaries were
copied, for operator!=() even twice as much.. in
for(...:GetColumnsRange())

(cherry picked from commit 581b8455)

 Conflicts:
         sc/inc/table.hxx

Use iterator pre-increment/decrement

(cherry picked from commit f599ff99)

079850116648dc69b8c92fa23b30233f63d9b6e7

Change-Id: I4b426ae855454544e50efca35aa73303138f7ba7
Reviewed-on: https://gerrit.libreoffice.org/50113Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>