New test cases have been added for molecular calculations with no
periodic boundary conditions. Compared to the already-tested periodic
systems, these calculations yield lattice vectors of zero and
have 3N-6 vibrational modes. This tests some different paths in the
parsing logic.

Based on a user report and sample files. Two main differences were
identified which caused the parser to trip up on a calculation without
periodic boundary conditions:

- No lattice vectors are printed in the output file, but the parser
  requires this data to exist, as does Abins' data format.

  - Here we apply the same convention as the Gaussian parser, setting
    lattice vectors to a 3x3 zero matrix

- The lowest 6 vibrational modes, which theoretically correspond to
  translation and rotation, are discarded from the output data. This
  breaks an assumption that there are 3N vibrational modes (where N is
  number of atoms). Abins in general does _not_ make this assumption,
  so it can be fixed in the parser.

  - Now the number of atoms is obtained from the coordinates data, and
    a check is made that the number of modes is either 3N or 3N-6. There
    _might_ be an issue with dimers (which have 3 translational modes,
    two rotational modes and a non-zero stretching mode); need to get
    access to Materials Studio and test this.

Some error messages were also cleaned up to remove a confusing "bytes"
type signature.

Update introduction to python documentation

Re #28920 - Fix norm runs for LRReductionWithReference

This commit plots the raw data from the input workspace, rather than the fit workspace (which often sees a reduced set of data due to applying fitting bounds)

Speed up function template browsers in indirect analysis GUI

Fix crash when switching backgrounds in ConvFit tab of indirect GUI

Merge branch '28914_AllowPaalmanPingsToRunOnElastic' of https://github.com/mantidproject/mantid into 28914_AllowPaalmanPingsToRunOnElastic

Update MSlice version in Mantid

Add Ubuntu 20.04 build dependencies list

The PaalmanPingsMonteCarloAbsorption algorithm and the indirect UI that
runs this algorithm both had small problems that prevented running with
elastic (diffraction\SANS) workspaces. These changes resolve those problems
which will allow some diffraction\SANS users to evaluate the abs correction
UI with a view to perhaps cloning or implementing something similar in their
own reduction UIs in future

This commit removes unnecessary replot calls, which slows the interface down. It does this throguh a RAII structure, which controls when redrawing occurs in the main plotting command.

- Modernise file opening
- Add namedtuple to sequence types, as it is a useful collections

Add output options to ConvFit

MantidPython and Notebook remove and add Docs

Fix typo in install rename command

Abins: remove unnecessary check on parameters dict when testing data loaders

Fix CTRQ performance test regression

Fix workbench launchscripts for windows package