[Feature Request] isSupported()

This is kinda a silly thing to request at first, but in the other freshplanet ANE there is sometimes a isSupported() function that really comes in handy while developing on a PC without throwing an Error.
It would be nice to have this in this repo as well to avoid Exceptions thrown around while not test on the device itself.

For now this can achieve the same thing:

    var softKeyboardSupport:Boolean = true;
    var softKeyboardHeight:Number;

    try {
        softKeyboardHeight = MeasureKeyboard.getInstance().getKeyboardHeight() as Number;
    }catch(error:*){
        softKeyboardSupport = false;
    }

    trace("softKeyboardSupport = "+softKeyboardSupport);

Cheers
Mortimer