This is a bugfix release:
- Fix compliance with max_inflight_messages when a non-clean session client reconnects. Closes one of the issues on bug #1237389.
- Fix incorrect inflight message accounting, which caused messages to go unsent. Partial fix for bug #1237351.
- Fix potential memory corruption when sending QoS>0 messages at a high rate using the threaded interface. Further fix for #1237351.
- Fix incorrect delay scaling when exponential_backoff=true in mosquitto_reconnect_delay_set().
- Some pep8 fixes for Python.