* 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
* Refactored BACnetShedLevel encoding, decoding, and printing into separate file. Added unit testing.
* Added API to load control object for shed-level, start-time, duty-window, full-duty-baseline, and enable.
* Fixed bacapp sprintf for shed level and host-n-port found in scan build.