re #17968

You can't group data if there is no data loaded, and you can't fit data
if there is no data loaded, so it makes no sense to use either of these
tabs before any data has been loaded.

This also avoids several bugs seen when users went to the Data Analysis
tab without first having loaded data - now this is not possible. You have to
load a dataset first, then you can go and fit it.

Left the Settings and Results Table tabs accessible as these could be used
whether or not there is a dataset loaded.

re #17968

Add option to sort direct beams by run numbers

Extract Q-values from vertical axis of a MatrixWorkspace

Fix MantidPlot and MantidQt unit tests for python 3

Add class DetectorInfo

LoadNexusProcessed can now handle the special case of TextAxis with empty label

Fix bug for LOQ batch mode

Enabled SavePlot1D to turn on/off the option to pop out canvas.

Fix exception and just return empty string

Fix many cppcheck v1.76 warnings.

Peak position diagnostic tool

This was a leftover from DetectorGroup and does not seem to make a lot
of sense.

Fix NMoldyn4InterpolationTest on master