0.1.5

• Updated volume_step_only logic to check volume after stepping, with some error checking. No longer uses volume_step_delta
• Support in-flight updating of ignored_zones param. Will re-query zones list, enable polling of unignored zones and disable polling of newly ignored zones.
• Require volume to be queryable to consider a zone active when querying
• Worked around race condition issue when using asyncio.wait_for (does not re-raise CancelledError if awaitable has already completed, eg. when update has been requested at the same time that the updater task has been cancelled due to scan_interval being changed)
• Optimised AVR polling to reduce unnecessary back-to-back polls
• Added more debugging