Improve Beam Centre Finder Log Level

[Peter Parker]

If a user has set the reporting level of the Results Log to too high a setting, the beam centre finder does not log any messages to it's text box.

Two possible solutions:

1. Allow the beam centre finder log lever to be different from the results log level.
2. Set the results log level to Information (or whatever is appropriate) for the duration of the centre finding routine, then switch back when finished.

Option 2 was suggested in the SANS meeting we had today, but option 1 seems the most sensible if it's possible.

[Stuart Campbell]

This ticket has been transferred to github issue ​10891