Release Name: 2.4.0

Notes:
== Rubygame 2.4.0

Release focus: Events.

=== Features

- New Events module, with a suite of new and revised event classes.
  The new classes offer full functionality as the older classes.

  - Use Rubygame::EventQueue#enable_new_style_events to enable the new
    event classes. This will become the default in Rubygame 3.0.

  - Uses symbols instead of integer constants for keyboard keys and
    mouse buttons (e.g. :a, :space, :mouse_left, :mouse_right).

  - Better unicode / international keyboard text input support.
    (See Rubygame::Events::KeyPressed#string)

  - More natural and memorable class naming scheme.

- New hook-based event handling system.
  (NOTE: Requires use of the new event classes.)

  - Rubygame::EventHandler class.
    EventHandler holds many EventHook instances. It handles each event
    by passing it to matching hooks.

  - Rubygame::EventHandler::HasEventHandler mixin module.
    Include this in your custom classes to add easy event handling
    and event hook creation abilities.

  - Rubygame::EventHook class.
    
  - Rubygame::EventActions module.
    Has several pre-made event action classes to use with EventHook.

  - Rubygame::EventTriggers module.
    Has several pre-made event trigger classes to use with EventHook.

- Added Rubygame.enable_key_repeat and Rubygame.disable_key_repeat.
  Thanks to atiaxi for this new feature!

=== Fixes

- Fixed: EventQueue#peek_each didn't yield any events.

- Fixed: Segfault in extract_rgba_u8_as_u8() on x86_64 systems.
  Thanks to ElCuGo for this fix!

- Fixed: Several "cast from pointer" warnings on x86_64 systems.

- Fixed: Build system didn't correctly compile with debug symbols
  when using "debug" option.

- Fixed: Surface#get_at didn't work correctly for 8-bit Surfaces.

- Fixed: Ftor.new_from_to would always complain about "wrong number
  of arguments". Thanks to atiaxi for this fix!

=== Other Stuff

- The panda demo (samples/demo_rubygame.rb) has been renovated to
  demonstrate how to use the new features, and to be a better example.

- Old event classes are deprecated and will be removed in 3.0.
  - ActiveEvent      (use Events::InputFocusGained,
                          Events::InputFocusLost,
                          Events::MouseFocusGained,
                          Events::MouseFocusLost,
                          Events::WindowMinimized, and
                          Events::WindowUnminimized)
  - ExposeEvent      (use Events::WindowExposed)
  - JoyAxisEvent     (use Events::JoystickAxisMoved)
  - JoyBallEvent     (use Events::JoystickBallMoved)
  - JoyDownEvent     (use Events::JoystickButtonPressed)
  - JoyHatEvent      (use Events::JoystickHatMoved)
  - JoyUpEvent       (use Events::JoystickButtonReleased)
  - KeyDownEvent     (use Events::KeyPressed)
  - KeyUpEvent       (use Events::KeyReleased)
  - MouseDownEvent   (use Events::MousePressed)
  - MouseMotionEvent (use Events::MouseMoved)
  - MouseUpEvent     (use Events::MouseReleased)
  - QuitEvent        (use Events::QuitRequested)
  - ResizeEvent      (use Events::WindowResized)



Changes: