This commit adds:
 - Icons and info for different types of windows/workspaces
 - A progress bar for workspace saving
 - A better, more flexible window layout

Nothing of the state is saved, but the window will now reopen if open
when the project was saved

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

This duplicates code, but we can rectify that later. This removes the
reliance on the AppWindow functions and allows us to create a plot from
the factory.

Far from finished, but this is a lot cleaner.

Using a different version number caused parsing to crash. Window numbers
were recoreded in th wrong place. Folders were not being written out
correctly.

Keeping the workspace save methods in there, as ApplicationWindow makes
use of them. But the method that handles generating the strings to be
saved can be moved to the new class.

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.

Next up loading project workspaces.

I think this is more descriptive about what it's supposed
to do. Also code further down uses TSVSerialiser, so the naming is
consistent.

This is mearly a checkpoint. New class compiles and has most of the
relevant bits in it for saving. Will now begin picking apart the GUI code from the
saving code.