Changelog:
===========
Build failures with older cython 0.29 series
Optimize processing of records in RecordUpdateListener subclasses
Speed up the service registry with a cython pxd
Optimizing sending answers to questions
Optimize unpacking properties in ServiceInfo
Refactor notify implementation to reduce overhead of adding and removing listeners
Add cython pxd file for _listener.py to improve incoming message processing performance
Cythonize _listener.py to improve incoming message processing performance
Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
