Currently OSX only properly supports floating windows in Qt if they
either have a minimise button or a maximise button but not both!! Here
we force the window to have a minimise button.

So it can be implemented by SliceWindow

We need to add the export macro to TSVSerialiser's class definition and
update the namespaces

This is so that it is accessible via widgets as well.

and using a static loading mechanism. This is so that we can revert to
using default constructors. Moved away from using the dynamic factory
class and instantiators as they cannot presently support this type of
instantiation mechanism.

Far from finished, but this is a lot cleaner.

Folders are a little special, so I've decied the code would be better
off in the ProjectSerialiser class. This is more consistent with how
loading works. ScriptingWindow now properly conforms to
IProjectSerialisable, with a small workaroudn for a MantidUI use case.

Also adds in missing includes that are now required.

The list of open files in the window is a list of absolute paths so
the new path needs to be made absolute before checking if it is open.
Refs #15682

The behaviour is then consistent whether the file was already open
or not as the currently active tab is the requested file.
Refs #15682

Refs #13417

Refs #13417

Refs #13292

Refs #13265

Refs #13265

Refs #13265

It is only implemented for the Python environment.
Refs #13265

Refs #13082

Refs #13082

Refs #13082

Refs #13082

Refs #6453

Refs #6453

Refs #10888