/* 
 * Return the type of this Joystick::Event object.
 *
 * Values:
 *   Joystick::Event::INIT
 *   Joystick::Event::BUTTON
 *   Joystick::Event::AXIS
 *
 * Example:
 *   case ev.type
 *   when Joystick::Event::INIT
 *     puts 'init'
 *   when Joystick::Event::BUTTON
 *     puts "button: #{ev.num}, #{ev.val}"
 *   when Joystick::Event::AXIS
 *     puts "axis: #{ev.num}, #{ev.val}"
 *   end
 *
 */
static VALUE j_ev_type(VALUE self) {