Log Message:
Add irrlicht-1.8.4 as graphics/irrlicht.
Based on work in pkgsrc-wip.

The Irrlicht Engine is an open source high performance real-time
3D engine written and usable in C++ and also available for .NET
languages.

It is completely cross-platform, using D3D, OpenGL and its own
software renderer, and has all of the state-of-the-art features
which can be found in commercial 3d engines.