Initial commit.
Add 'irrlicht/' from commit '78ca1053c8e2eb6f4e368f431059086a8575efaa'

git-subtree-dir: irrlicht
git-subtree-mainline: ae1923c514b4f65534f4b49396190614b8f52c2b
git-subtree-split: 78ca1053c8e2eb6f4e368f431059086a8575efaa
Added irrlicht for visualization.