Initialize menu with class and use proper positioning
Return whether UnregisterHotkey() worked or not
Add shutdown routine.

This unhooks the mouse and keyboard, unregisters the hotkeys, and then deletes the HKM instance.
Post a WM_CLOSE when the appropriate context menu item is clicked
Add method to hide notification icon

This is required to avoid leaving "ghost" icons in the tray.
Fix typo
Graceful shutdown routine