Support dclab plugin and ml features in Shape-Out2

[PinkShnack]

Plugin features are a way for users to define their own features within dclab. The original dclab issue is here and the soon to be merged PR is here.

These should be available in Shape-Out2.

[maikherbig]

I would be highly interested in that feature!!!

[paulmueller]

Thanks! We are currently very busy with other projects, so don't expect this to be implemented within the next month.

[paulmueller]

Before this can be implemented, we need DC-analysis/dclab#144 and DC-analysis/dclab#143.

[paulmueller]

TODO:

• tests
• docs
• include tensorflow in builds (not for now)