Refs #21229

Refs #21229

Refs #21229

Refs #21229

Refs #21229

Import mantid in testhelper.testrunner

This ensures all paths to script modules are set up from the start. Without
this several tests are failing to find their required modules. In the
future we should work towards using .pth consistently.
Refs #0

Indirect - Data Analysis Interfaces - Decrease Size of Difference Preview Plot

GSASIIRefineFitPeaks reintegrated with latest version of GSAS-II

Adjust MonitorEfficiencyCorUser for other instruments

provide a user file column in the data table

Upgrade UI and preprocessing for HB3A

Refactor ExtractSpectra to add MPI support

BASISReduction: exclude one time period from the reduction

Hyspec spin incoherent polarization

Removed the "Test the Curve Fit widget" interface

Create basic mantidqt package layout

Remove crash in debug build in LoadISISNexus

Port some algorithms for MPI

Parallel event loader

Refs #21178