Import/Export Yaml

[zwischenloesung]

Add down- and upload from/to *.yml as an archive (well then, .zip for foobars sake...). I have in mind something like the class/nodes structre used in reclass. We will have to rewrite it anyway (see our maestro.py repository).

[zwischenloesung]

The position information (or future "configuration") can maybe put in a separate descriptor .json? On load the elements without such info will (semi-)randomly be placed...