Cross-platform Quit menu item display is awkward

[machawk1]

In Windows, the Exit menu is often the last entry in the File menu, which is displayed as the most-left menu.

The current implementation in Windows, to align with macOS, displays QUIT (note, all-caps) in the Help menu, which is the last menu in the horizontal series and QUIT is the last entry in this menu.

wxPython does something strange in macOS (by design) that requires this entry to be in the "help menu" to display in the WAIL menu on macOS. TODO: Match the paradigms to the platforms.

About is often the last entry on Windows and has the "A" menu shortcut/accelerator, which is not currently present in WAIL for Windows (from src)

[machawk1]

In 58a751c :

• Move Quit from Help to File menu
• Rename Quit to Exit
• Move About... to bottom of Help menu
• Add shortcut for About entry (and others)

[machawk1]

Per the Issue title, the menus are now less awkward across platforms, so closing it with shortcuts to be addressed later.