not really useful yet...

Scenery::connect_nodes return () instead of EdgeIndex since it's not
needed anaywhere.

Fixed tests for group. All tests pass again.

Remove example trait_test.
Doc fixes.

Optical::name returns node type as default.

Source: add name parameter.

This forces the usage of the "new" function to submit a name.

Update examples accordingly

Separate Dottable trait to additional file.

Add unit tests.

The original graph is kept untouched.

This is only a preliminary solution until we have a general reporting.

Copied from EnergyMeter. Needs modifications yet.

Update docs. Update filter_test example.

Update documentation.

Make some functions private.

If a port mapping was defined and group noed connected afterwards,
port maps might become invalid.

Check now if input / output nodes are half-connected.
Add unit tests accordingly.