Actually make the 2-byte atomics work.

Even though I tested the 1-byte operations on arbitrarily aligned bytes,
it seems I did not do this for the 2-byte operations.

Create easy to read functions that are used to get/put bytes and
halfwords in words. To keep the compiler happy, explicitly read two
bytes into a union to obtain a 16-bit value.
Remove extraneous characters ('<<<') from `Exit' menutag in the "Security"
and "Startup"->"Misc" modules to make the menus appear more consistent with
the numerous other modules and look a little cleaner.

PR:		ports/169316
Reduce verbosity in the "Console"->"Saver" module (bsdconfig syscons_saver)
by replacing the infinitive [verb] phrase "Simply blank the screen" with a
simple description of what you get; "Blank screen".

PR:		ports/169316