Implemented range/iteration (idea of Annabelle)

Annebelle suggested to have a range/iteration options, something like in
the PaganinItarator.
She made a first implementation, which I copied over.
This led to the adjustment of some option-names, so changes might be
disruptive for others...
Needs quite some tests before merging into master.
Merge branch 'master' of https://bitbucket.org/psitomcat/beamline-scripts into delta-range
Merge branch 'delta-range'

Conflicts:
	postscan/PaganinIterator.py