Drop usage of obsolete API (#22)

Author: ktf

DebugGUI/src/imgui_impl_glfw_gl3.cpp

@@ -330,7 +330,6 @@ bool    ImGui_ImplGlfwGL3_Init(GLFWwindow* window, bool install_callbacks)
     io.KeyMap[ImGuiKey_Y] = GLFW_KEY_Y;
     io.KeyMap[ImGuiKey_Z] = GLFW_KEY_Z;
 
-    io.RenderDrawListsFn = ImGui_ImplGlfwGL3_RenderDrawLists;       // Alternatively you can set this to nullptr and call ImGui::GetDrawData() after ImGui::Render() to get the same ImDrawData pointer.
     io.SetClipboardTextFn = ImGui_ImplGlfwGL3_SetClipboardText;
     io.GetClipboardTextFn = ImGui_ImplGlfwGL3_GetClipboardText;
     io.ClipboardUserData = g_Window;