Added  functionality to main window

Selecting File -> Save will now prompt for a file name in the windows
explorer.  Does not yet save when selected.

Selecting File -> Load will now prompt for a file name in the windows
explorer.  Does not yet have load functionality when selected.

Selecting File -> Quit will prompt the user with a dialogue box asking
"Would you like to save: Yes No Cancel"

Selecting yes will allow the user to save before exiting
Selecting no will exit without saving
Selecting cancel will return to the system

- Tyrone