Test/Learn Dear ImGui
https://github.com/ocornut/imgui
git clone --recursive
git submodule add https://github.com/ocornut/imgui.git external/imgui
git submodule update --init --recursive
git add .gitmodules external/imgui
git commit -m "Added Dear ImGui as a submodule"
git push
git pull origin master
git add external/imgui
git commit -m "Updated ImGui submodule to latest version"
git push
git submodule update --init --recursive
make
make test
make test DEBUG=1