Reduced number of points logged during statistics - added threshold and individually log changes in a series.

Changed each series so that they only log changes when the series changes (before it would log a point any time there was a change in any setting).

Turned off the 'raw' logger by default.  Good for debugging but makes a large log that's not needed.

Added a threshold for logging changes - if temperature changes are smaller than .15, then it waits until the temperature changes more than that to log the point.  This is primarily to clean up the fluctuations when the temperature is between points and the sensor would alternate between them.  This significantly reduces the number of points and cleans up the plots a lot.  If desired, this could be a configuration option as it uses the THRESHOLD variable, but for now it's hard coded.