function getKeymap(defaults) {
        return $.extend({}, defaults ? _defaultKeyMap : _keyMap);
    }
Returns a copy of the current key map. If the optional 'defaults' parameter is true,
then a copy of the default key map is returned.
@param {boolean=} defaults true if the caller wants a copy of the default key map.
                           Otherwise, the current active key map is returned.
@return {!Object.<string, {commandID: string, key: string, displayKey: string}>}