Configure plugs from your procedure file

Plugs can now receive settings like instrument addresses directly from your procedure file, so you no longer have to hard-code them in Python or duplicate a plug class per instrument.

• Added an optional config mapping on each plug that is passed to the plug class as keyword arguments
• Added support for running several instruments of the same model by giving each plug its own config
• Documented the new config option and the multi-instrument pattern in the plugs guide