Remove BigMenu Logic

When BigMenu exists, NavBar assumes you want 'DONT_SHOW' for
left/right little menus.  This had spacing implications for users
that used BigMenu, but few buttons :
http://rootzwiki.com/topic/38274-menu-button-in-navbar/
removing this had little implication on the NavBar itself, but
did force some re-working of the MenuArrowKeys.