Mean of angles calculated wrong

Applying multiple measurements on angles and then summarizing the results (RMB => Summarize) does not take into account that it is dealing with angles. E.g. the means are calculated by simple averaging instead of vector averaging.

Start from the RMB => Summarize workflow described in the issue and locate the code that calculates means for angle measurements. Verify the current simple averaging behavior, then confirm that summarized angles use vector averaging, including measurements near the wraparound boundary.

Written by the indexing model from the issue text.