Multiple commits. See release notes.

[MarkusFrankATcernch]

BEGINRELEASENOTES

• Implemented issue Changing Geant4 physics flags  #1010: Changing Geant4 physics flags
  o Extended the Geant4UIManager to support command queues at various stages of the program:
  -- configure
  -- initialize
  -- pre-run
  -- post-run
  -- terminate
  o Added interface function to directly communicate with the G4UI using string commands at any time
  from python.
  o Extended Geant4Kernel functionality to allow client actions to subscribe to stages of the program
  and perform dedicated actions on:
  -- configure
  -- initialize
  -- terminate
  As an example please see DDG4/src/Geant4UIManager.cpp

• Dropped issue DDG4: Particle charge is not properly propagated from the input stage to the output stage #1004 after some tests and investigation:
  This issue cannot be resolved, because MC records may also be read without Geant4 and a physics list being initialized.
  Hence the event readers cannot implement such a feature if the event record does not support charge, but only the PDG code.
  Conclusion is to best update the charge of particles at the output stage using the PDG code or to implement an event action,
  which performs this actions right before the output stage.

• Simplified component properties.

• Improvements to DDDigi (work in progress)

ENDRELEASENOTES

[andresailer]

Suggested change

	Strings may be emraced by quotes: '<value>'
	Strings may be embraced by quotes: '<value>'

[andresailer]

Suggested change

	return eval(data)
	import ast
	return ast.literal_eval(data)
	except ValueError:

https://docs.python.org/3.7/library/ast.html#ast.literal_eval
Safely(!) eval

>>> import ast
>>> ast.literal_eval('foo')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python2.7/ast.py", line 80, in literal_eval
    return _convert(node_or_string)
  File "/usr/lib64/python2.7/ast.py", line 79, in _convert
    raise ValueError('malformed string')
ValueError: malformed string
>>> ast.literal_eval('"foo"')
'foo'

[andresailer]

Should add a check for success