Configuration file

[joppi588]

Command configuration is currently hard-coded into viCommand.py
Motivation was to have an easier configuration than via the XML files from original vcontrold

Proposal: Use JSON configuration files instead
Benefit: Adapt to different control units

TODO:

• Specify configuration file: As parameter to vicontrol.init(...)? Default value?
• Read configuration file.
• verify configuration file structure, e.g. ensure that only read/write/function_call is used as access mode
• Design: Read at the time vicontrol is initialized and then pass to vicommand?