The tablet UI can be long lived, unlike the previous VRMenu.
So instead of using a dynamic mapping that was only enabled when the VRMenu was shown, standard_navigation.json.
standard_navigation is always active. Also, standard_navigation.json has been changed.
Left and Right click and stick events never become UINav events. Only Dpad A, B, X, Y, LB and RB are mapped to UINav events.
Help button has been updated to switch to the help.html. It doesn't look good because
the content was authored expecting landscape window, not portrait.
The API is by no means final. But it exposes two methods to JS.
* Tablet.gotoHomeScreen() - Used to forcefully go back to the home tablet "springboard", eventually this will
hooked up to the tablet button.
* Tablet.gotoWebScreen(url) - Causes the tablet to switch from the home "springboard" and load a web url.
tabletTest.js and help.js have been updated to use this functionality.
