[Server] 2.3.16 released

This unstable release is the latest in the bleeding edge of development.  This release focuses on fixing a critical bug in 23.15 where motion detection was not working properly and a bug in 2.3.14 where an error popped up stating changes could not be saved.

Better caching has been added for the Events database, so events should load faster in the client.

We are working on gearing up for a 2.4.0 release and most of the features in 2.3 will be included in 2.4, so please report any issues to us as soon as possible.

Download instructions for the unstable repository can be found here.  Please post questions or comments to the unstable / bleeding edge forum (community.bluecherrydvr.com).  It is not possible to downgrade from the unstable release back to the stable release without completely removing and reinstalling the software (including the database).

The following changes were added in this release:

* Improve events fetching performance by adding index on DB table EventsCam, on field `time`
* Fix a bug of settings updating introduced in 2.3.14.
* Workaround for motion detection breakage in 2.3.15
* Fix SQL query syntax error at recordings max age check
* Sliding time window based motion event detection: introduce minimal count of processed frames (hardcoded to 4)
* Decrease log level of debugging message
* Effectively silence messages about lacking motion_analysis_{stw,percentage} DB fields