message: Add forgotten Focused hint
  This hint [has existed for some time](https://github.com/glfw/glfw/blob/089ea9af227fdffdf872348923e1c12682e63029/docs/news.dox#L322) but somehow was forgotten in glfw-rs. This commit just adds that.
diff: @@ -901,6 +901,7 @@ impl Glfw {
  WindowHint::Decorated(is_decorated) => unsafe { ffi::glfwWindowHint(ffi::DECORATED, is_decorated as c_int) },
  WindowHint::AutoIconify(auto_iconify) => unsafe { ffi::glfwWindowHint(ffi::AUTO_ICONIFY, auto_iconify as c_int) },
  WindowHint::Floating(is_floating) => unsafe { ffi::glfwWindowHint(ffi::FLOATING, is_floating as c_int) },
  + WindowHint::Focused(is_focused) => unsafe { ffi::glfwWindowHint(ffi::FOCUSED, is_focused as c_int) },
  WindowHint::ContextNoError(is_no_error) => unsafe { ffi::glfwWindowHint(ffi::CONTEXT_NO_ERROR, is_no_error as c_int) },
  WindowHint::ContextCreationApi(api) => unsafe { ffi::glfwWindowHint(ffi::CONTEXT_CREATION_API, api as c_int) },
  WindowHint::ContextReleaseBehavior(behavior) => unsafe { ffi::glfwWindowHint(ffi::CONTEXT_RELEASE_BEHAVIOR, behavior as c_int) },
  @@ -1410,6 +1411,10 @@ pub enum WindowHint {
  ///
  /// This hint is ignored for full screen windows.
  Floating(bool),
  + /// Specifies whether the windowed mode window will be given input focus when created.
  + ///
  + /// This hint is ignored for full screen and initially hidden windows.
  + Focused(bool),
  /// Specifies whether the OpenGL or OpenGL ES contexts do not emit errors,
  /// allowing for better performance in some situations.
  ContextNoError(bool),
  