Do all event handling on resize rather than orientationchange

In my testing, onresize is called, and within it the correct, new
browser width is available. Greatly improves behaviour in Chrome and
Firefox on Android 4.4.4, and stock browser in Android 2.3.
Ensure meanStyles is correctly initialised in showMeanMenu()

Ensures correct centering of reveal button when meanRevealPosition =
'center' in all circumstances
Ensure removeElements removed when meanmenu visible

At present, removeElements are removed whenever the toggle is clicked
(whether to open or close the menu). This patch removes them whenever
the meanmenu is visible.