implement "typical" save and close conventions.

implement "typical" save and close conventions.
After running an analysis if it hasn't been saved, and you try to close
the window, mussa will ask if you want to save, not save, or cancel the close.
Saving also uses the recently implemented tracking the analysis_path to
determine if it should just offer to save or to use save as.

the only real issue is the dirty flag might get tripped for things
that aren't actually being saved yet.