mode_RPiHQ_mean.cpp: precision
mode_RPiHQ_mean.cpp: precision

* Use consistent precision (%1.3f) for mean-related numbers.
* Add apostrophe to precision to add thousands-separators to make large numbers easier to read.  Unfortunately they aren't added in the fractional part of numbers (a Linux bug?)
* Deleted an unneeded comment.
thomasjacquin/allsky,thomasjacquin/allsky,thomasjacquin/allsky