Added a new API for writable property lists across all the basic example object types, preparing for the introduction of a Writable_Property_List property in every object in a future BACnet standard revision.
The lists can be used by backup and restore feature to automatically choose the object property values in the backup that can be restored via internal WriteProperty directly from BACnet CreateObject services with List of Initial Values.
Updated existing device object examples to include these writable property lists.
* Added a new getter API function Timer_State_Change_Value_Get() to the timer object that returns state-change values by copying them to a caller-provided buffer, providing a safer alternative to the existing Timer_State_Change_Value() function which returns a direct pointer to internal data.
* Added basic timer object, internal state machine, and unit tests
* Added BACnetTimerStateChangeValue encode, decode, parse, print, and diff with unit tests
* Changed handler of add/remove list element to check if the property is a BACnetLIST
* Added BACnetLIST utility for handling WriteProperty to a list.
* Fixed outlier ReadProperty object handlers to return zero when the RP parameter is NULL.
Steve Karg