Creating both WebView and GLFW windows prevents the app from ever exiting (OSX only)

[rdw-software]

When creating a WebView window and a GLFW window in the same application, the app can never exit normally (fall through the event loop and then shut down) even if both windows are destroyed and GLFW de-initialized. Presumably, there's a conflict between both libraries trying to manage the application's lifecycle via app delegates and related mechanisms.

The problem is only present on Mac OS, so I opted to proceed with integrating GLFW anyway and look into this later.

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Almost certainly requires #201 since the OSX code is highly problematic.