SectionManager: Copy list before extending

If the list doesn't get copied, the local_bears list will actually be
extended. There will be a test added to avoid this in a later commit
after the SectionExecutor was added.
ProcessSpawner: Allow delayed process starting

This is usefull if you work with queues. In this case you'll want to
first create the processes and then fill the queues and finally start
the processes so they'll get the elements.

I didn't fully understand yet why this is necessary but it would be nice
to have this understanding.
processes: Add SectionExecutor
processes: Add SectionExecutorTest
SectionManagerTest add