Re #7736. Consistently use the same code for bad fits.
Re #7736. Actually use the MinimumPeakHeight parameter.

It was passed into FindPeaks, but not checked again in
GetDetOffsetsMultiPeaks. Also check for negative chisq being
being returned.
Re #7736. Exposing MinimumPeakHeight through py-algorithm.
Re #7736. Refactored FindPeaks to simplify code (slightly).

This included:
 1. Only calculate the peak center once
 2. If the guessed peak width is < 1e-200 then don't bother fitting
 3. estimatePeakParameters just returns the error message if there
    is one.
Re #7736. Reduce the d-range that is used for finding peaks.

This is really just looking for where there is actual data (non-zero
counts) and fitting that. There are also changes for reducing the
number of uninteresting log messages.
Re #7736. Cleaned up information in InfoTableWorkspace
Re #7736. Bringing all background estimations into one place
Merge remote-tracking branch 'origin/feature/7736_calibrate_pg3'