Upstream SequenceLoader from ILDConfig

[Zehvogel]

BEGINRELEASENOTES

• Upstream the SequenceLoader from ILDConfig, it is used by both CLD and ILD.

ENDRELEASENOTES

[tmadlener]

Can we add a small test for this? I think it should be fairly straight forward with the functional examples that we already have to make one where we

• use the ExampleFunctionalProducer to create some MCParticle collection and put that into a (trivial) sequence in a separate file
• Load that sequence in the main config and run the ExampleFunctionalConsumer from there (or if we go for really fancy put that into a second file and load that as well).

[Zehvogel]

@tmadlener I added a test but accessing the sequence became a bit ugly, maybe you have a better idea... This is about as much time as I can invest at the moment.

[tmadlener]

Thanks for adding the test. For now I have added a slightly more generic version of load to make it possible to work around the conversion that we have chosen in ILD and CLD (just in case).

I have also added a bit of documentation to make sure that it's clearly stated that the sequence will be loaded relative to the working directory unless given as an absolute "path".

The one option that would make this possible otherwise would be to add an optional base_path argument to the constructor of the SequenceLoader and to then import relative to that if it has been specified. I am not entirely happy with that either though as it gives the whole thing even more state to keep track of.

[tmadlener]

Are we still waiting on something here? Should we still take a look at how ATLAS and LHCb deal with this?