Add time average to "Sample Logs..." window

[Peter Peterson]

This has two components:

1. Add a timeAverageValue() to TimeSeriesProperty. The start of this method is hiding in averageValueInFilter.
2. Expose the new method to python
3. Show the result in the window as an additional value. If something is not a TimeSeriesProperty then this field should be blank.

[Peter Peterson]

Re #7875. Adding TimeSeriesProperty::timeAverageValue

Changeset: 8d5afdf258110df511f558dde287c06183b3f276

[Peter Peterson]

Re #7875. Exposing TimeSeriesProperty::timeAverageValue to python.

Changeset: de163f65e5888d99eb08dfeb22946fa19c5a1b44

[Peter Peterson]

Re #7875. Added time average value to sample log window.

Changeset: fcf34654f6a8ed381256a2479023cd59ad1bd15c

[Peter Peterson]

This is on ​feature/7875_time_avg_value.

To test: This can be tried with other values, but I found a run and log that shows a difference since that is harder to find.

• Load SEQ_32464_event.nxs
• Right-click the workspace and see "Sample Logs..."
• Plot the log "svpressure" and look at the statistics for it. Since there is the same number of values at the min and max, the average is just halfway between. The time-average is lower because there is more time spent at the minimum value.

[Michael Reuter]

Merge remote-tracking branch 'origin/feature/7875_time_avg_value'

[Stuart Campbell]

This ticket has been transferred to github issue ​8720