[INTERNAL] replaced SubMonitor usage in OPN

OPN now used the SubProgressMonitor class from the core.

Also fixed an issue in the SubProgressMonitor where one suppress flag
got a wrong value assigned.

Change-Id: Iea0ae9fce1bc9ae03f9042f59b270e8ed3073b1d
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1825
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>