[Feature] Reject outliers in plots

• This change implements an outlier filter for live plots and the web interface. It excludes values from the plot range calculation that are at the very edge of the value distribution and very different from the remaining values. In particular, this fixes plots of Dectris detector data where their acquisition software sets dead pixels to the maximum possible value. This improvement is particularly important for the web interface and for live plots since they currently do not allow setting the plot range manually. The value zero is excluded from the statistical evaluation to avoid cutting off the few non-zero pixels in low-dose datasets (#1310 #1742).