* [toggleswitch] Add support for key navigation to this widget
Add the onFocus an onUnfocus event handler
add a new function that just circle the switch if not touch event is
detected
* Add key navigation to the readermenu
The shortcut is still Alt-gr on sdl, to be defined on Kindle
* Remove the old method of handling the Press key.
Now the event is handled by the main widget who implement focusmanager
and then dispatched to the currently focused item.
Modify the fine font tuning only for non touch-devices
See : https://github.com/koreader/koreader/pull/3785#issuecomment-375306466