first try on Policies to configure output

 - each output feature is it's own policy
 - currently, an instance is necessary. this should be only
   type-dependent in the future (this branch is not complete yet!)
Policies fully working

 - a policy for each sub-feature
 - currently, each policy does all the computing
cleanup for all files

 - progressbar now also consists of the policy classes, but is not as
   flexible. The idea is to provide an easy to use default
   implementation that just works as it used to
 - there is still the legacy version of the progressbar
added some nicer comments