improve control chart selection of what to display

[fdion]

When there are over limit (default 1000, shouldn't be set much higher, unless output is svg and viewer can scale), we limit the number of points displayed. If we look at a slice (say, an hour or a day) this is usually not a problem. When fully zoomed out, however, we need to improve the presentation of OOC points. (calculations are done on all the data, no matter what is displayed).

[keryookery]

thanks，it's useful. i also want to know if it is tha same for the use of individual observations in T chart