* Added callback API for extending the basic Device object and children with proprietary properties for ReadProperty and WriteProperty services. The callback API includes a function to get the specific proprietary property list for any specific object instance in the device, functions to handle the ReadProperty or WriteProperty of the proprietary property.
* Added a new property_list_function typedef to proplist.h for proprietary property list callbacks
* Removed the object-specific proprietary property implementation from the Loop object
* Added test coverage in the Device test validating the proprietary property API usage
Steve Karg