C++: Fixed ptr bug
C++: use set() function instead of wonky assignment operator overloading; rearranged class structure to match C API.
Test for forbidden keys in msig_set_property() and mdev_set_property().
Swig/Python: return timetag from start_queue() function.
Do not check for expired devices on every call to monitor_poll().
Use link pinging for estimating clock offsets, network latency and jitter between peers instead of admin-bus /sync messages. Simplify outgoing /sync messages but still accept old version.
Improvements to link sync.
C++: Fixed problems handling property values that are arrays/vectors of strings.
Switched properties named 'n_<something>' to 'num_<something>' for consistency.