equipment_id for merged configs and routed nodes

Add a new custom module property 'original_id' indicating
the equipment_id the modules originally belongs to.
This property is only given, when distinct from the equipment_id
of the SEC node.
It happens when multiple config files are given, for all modules
but the ones given in the first file, and for routed modules,
when  multiple nodes are routed or own modules are given.

+ fix an issue in router: additional modules were ignore in case
of a single node.

+ small cosmetic changes in config.py reducing IDE complains

Change-Id: If846c47a06158629cef807d22b91f69e4f416563
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/35396
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

test/test_modules.py

@@ -243,7 +243,7 @@ def test_ModuleMagic():
         'export', 'group', 'description', 'features',
         'meaning', 'visibility', 'implementation', 'interface_classes', 'target', 'stop',
         'status', 'param1', 'param2', 'cmd', 'a2', 'pollinterval', 'slowinterval', 'b2',
-        'cmd2', 'value', 'a1', 'omit_unchanged_within'}
+        'cmd2', 'value', 'a1', 'omit_unchanged_within', 'original_id'}
     assert set(cfg['value'].keys()) == {
         'group', 'export', 'relative_resolution',
         'visibility', 'unit', 'default', 'value', 'datatype', 'fmtstr',