Multiple commits. Please see release notes.

[MarkusFrankATcernch]

BEGINRELEASENOTES

• Verify and enhance the possibility to import plugin definitions from an external XML file
  (See isue: Impossible to include plugin definitions from an external XML file #1062).
  The corresponding examples are:
  -- minitel_config_plugins_include_command_line, which shows how to perform the task by parsing sequentially the
  XML input files like:

  $> geoPluginRun -input <path>/compact/MiniTel.xml  -input  <path>/compact/ExamplePlugins.xml
  

-- minitel_config_plugins_include_command_xml, where the second XML file is simply included:

  <includes>
    <file ref=<path>/examples/ClientTests/compact/BoxTrafos.xml/>
    <file ref=<path>/examples/ClientTests/compact/ExamplePlugins.xml/>
  </includes>

where BoxTrafos is the entire original XML containing the geometry.

• Add plugins: configure Volume/SensitiveDetector object instances from information in XML Nodes. Given an XML tag like:

   <plugin type="config" name="DD4hep_DetElementConfig" path="/world" debug="true">
     <volume>
        <regionref   name="world_region"/>
        <limitsetref name="world_limits"/>
        <visref      name="world_vis"/>
     </volume>
   </plugin>```
  

Can be used directly to modify the settings of s DetElement identified by its path. Similar for sensitive detector objects:

    <plugin type="config" name="DD4hep_SensitiveDetectorConfig" detector="MyLHCBdetector5" debug="true">
      <combine_hits    value="true"/>
      <verbose         value="true"/>
      <type            value="tracker"/>
      <ecut            value="5*keV"/>
      <hits_collection value="hits_collection_5"/>
    </plugin>

• This construct also allows to configure the world volume as part of the resolution of issue How to define a limitset applicable to the whole world? #1064

  <world debug="true">
   <regionref   name="world_region"/>
   <limitsetref name="world_limits"/>
   <visref      name="world_vis"/>
  </world> 
  

  Technically the implementation are XML utilities, which are used both by the plugin and the Compact converter.

• Propagate the changes to the world volume to Geant4, which was not possible with DDG4 before, because production cuts and region settings for the world volume belong to Geant4 and are managed by Geant4. (also How to define a limitset applicable to the whole world? #1064)

• Side product: Add debug flags for the G4 LimitSet conversion. To enable the flags in the python setup:

    seq, act = m.geant4.addDetectorConstruction("Geant4DetectorGeometryConstruction/ConstructGeo")
    act.DebugLimits = True
  

• Have the maps in DetectorData being named to ease debugging.

• Add some XML attribute conversions (more user friendliness)

• Add accessors to the PlacedVolume and the Volume handles to access the class name of the implementing class.

• DDDigi: Add passing event parameters to the output and from the input record to the store. Needs testing though,
  but this requires a new release of podio.

ENDRELEASENOTES