Required for access to the new mantidqt module

It caused an additional linker flag, -L/usr/lib/x86_64-linux-gnu, to
be added where ever the GSL_LIBRARIES variable was used. On Ubuntu 18.04
this seems to cause the linker to pick libomp over libgomp and when a
library built with GSL_LIBRARIES is then linked to an executable
built without it we get the executable link to both libomp and libgomp
resulting in undefined behaviour.

when running systemtests

TableWorkspace has all columns editable by default. PeaksWS has all columns read-only by default.

Values in editable cells can be changed. Changes are reflected in the underlying WS with the correct type.

TWD Model uses same "allowed workspaces" idea as MatrixWorkspaceDisplay

This more closely mimics Ninja

If a previouus build exists the script checks whether
the compilers match and cleans the build directory if they do not
Refs #0

Will terminate all Xvfb processes and remove any leftover Xvfb X server
lock files.

Should be used when a build fails with error messages saying that Xvfb
failed to start.

If the build continues to fail on the same server then something may
genuinely be horribly wrong.

This is a follow on to #24057

Creates an X server for unit tests and user documentation generation and
tests.

It is required by boost::filesystem

This is now handled completely within the mantid __init__ itself
as once the mantid package has been found then the correct
location of the properties file is already known. Anything else
should just mean a broken installation and an ImportError
is raised.

This is more standard and removes the possibililty
of users to accidentally overriding the set of python
paths required by many interfaces to start.
The pythonscripts.directories config key is now empty by
default and only adds directories on starting the framework.

It is set at the start of main so don't duplicate things.

Matches the behaviour of the linux scripts

The issue is that virtualenv doesn't add all of the platform packages
when asked for `--with-system-site-packages`. This attempts to automate
the fix.

This appears to be something characterized in
https://github.com/pypa/virtualenv/issues/874.

Defaults to qt4