Adapted from the OpenGL 3 reference implementation of ImGui under the provisions of the MIT license at:
https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_glfw.cpp
https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_opengl3.cpp
https://github.com/ocornut/imgui/blob/master/examples/example_glfw_opengl3/main.cpp
