Used for Geometry debug flags

DDSim: compactFile can only be one instance, otherwise we cannot overwrite what is in the steeringfile, still takes multiple XML files

From https://stackoverflow.com/a/41153081

Needed for python2.7 compatibility

DDSim: Add logic to add help for non-property helper variables, add logic to add choices for all helper options

if not specific filter is set the default filter for tracker or calorimeter is applied (if a default filter is set)
To turn off all filters just assign an empty string, empty list or None to the mapDetFilter

update doc

Move applyFilter to Helper/Filter
Adapt steeringFile

ddsim: remove some commented lines, add dump[Parameter] flag to just print the configuration parameters

* Move DD4hepSimulation et al into python module DDSim, needed for proper
  importing

* Can now control magneticfield setup, gun, particle handler, output via command
  line.

** added ConfigHelper and daughter classes implementing these options
   DDSim/DDSim/Helper, easily extensible to additional features

** also easier changing of these parameters via steering file See
   example/steeringFile.py

*** No more functions, no more "global GeV"

** --help string can be given by using @property, see e.g. Helper/Output.py

* added optional argcomplete, allows command line "tab"complete for all command line options (and values!)
  Needs argcomplete (sudo pip install argcomplete), bash completion and bash (or zsh).
  and 'eval "$(register-python-argcomplete ddsim)"'

* move import statements to reduce startup time until "--help", mandatory to
  reduce latency for argcomplete