Add glfwInitHint

This allows setting hints that control how the library is initialized,
transforming more compile-time options into run-time ones.

docs/intro.dox

@@ -31,6 +31,7 @@ successfully initialized, and only from the main thread.
  - @ref glfwGetVersion
  - @ref glfwGetVersionString
  - @ref glfwSetErrorCallback
+ - @ref glfwInitHint
  - @ref glfwInit
  - @ref glfwTerminate
 
@@ -61,6 +62,42 @@ allocated by programs that simply exit, but GLFW sometimes has to change global
 system settings and these might not be restored without termination.
 
 
+@subsection init_hints Initialization hints
+
+There are a number of hints that can be set before initialization, that affect
+how the library behaves.
+
+The values you set are not affected by initialization or termination, but they
+are only read during initialization.  Once GLFW has been initialized, setting
+new hint values will not affect behavior until the next time it is terminated
+and initialized.
+
+Some hints are platform specific.  These are always valid to set on any
+platform but they will only affect their specific platform.  Other platforms
+will simply ignore them.  Setting these hints requires no platform specific
+headers or calls.
+
+
+@subsubsection init_hints_osx macOS specific hints
+
+@anchor GLFW_COCOA_CHDIR_RESOURCES
+__GLFW_COCOA_CHDIR_RESOURCES__ specifies whether to set the current directory to
+the application to the `Contents/Resources` subdirectory of the application's
+bundle, if present. 
+
+@anchor GLFW_COCOA_MENUBAR
+__GLFW_COCOA_MENUBAR__ specifies whether to create a basic menu bar when the
+first window is created, which is when AppKit is initialized.
+
+
+@subsubsection init_hints_values Supported and default values
+
+Init hint                       | Default value | Supported values
+------------------------------- | ------------- | ----------------
+@ref GLFW_COCOA_CHDIR_RESOURCES | `GLFW_TRUE`   | `GLFW_TRUE` or `GLFW_FALSE`
+@ref GLFW_COCOA_MENUBAR         | `GLFW_TRUE`   | `GLFW_TRUE` or `GLFW_FALSE`
+
+
 @subsection intro_init_terminate Terminating GLFW
 
 Before your application exits, you should terminate the GLFW library if it has