Use AddDBButtonToHeader in update_header.

fixes nEDM-TUM/nEDM-Interface#13
Cleanup and making the functions in nedm-base protected.

Rearrange/clean some code.

Make using_prefix private.
White space changes.
Use global changes feed (i.e. events) in monitoring graph.

address nEDM-TUM/nEDM-Interface#14.

Use events instead of changes feed in control code.

Address nEDM-TUM/nEDM-Interface#14.