json serializable / net store to disk with data source

[FlorianShepherd]

If a net contains a datasource (inside a controllor) the saved file net.json may be quite large.

Todos:

• add more data sources (csv)
• add a warning if the file will be large (check size of datasource before storing). Add to to_dict() function of datasource
• deepcopy fail for net

[lthurner]

@FlorianShepherd what is the status here?

[FlorianShepherd]

@rbolgaryn is assigned. I didn't integrate more datasources / added the warning and just created this issue during the pp meeting.