Irrlicht Port to vcpkg

This is a port of irrlicht to vcpkg (https://github.com/Microsoft/vcpkg/)

Usage:

1. create a new folder in vcpkg-root/ports/ called irrlicht
2. Copy the files CONFIG,portfile.cmake,CMakeLists.txt to that.
3. Use vcpkg as common e.g. vcpkg install irrlicht (for x86, dynamic) or vcpkg install irrlicht:x64-windows-static (for x64 static)
4. In your programs CMakeLists.txt just use FIND_PACKAGE(irrlicht) and use it like any other lib

The Irrlicht sourcecode an the dependencies zlib, libpng, libjpeg, and bzip2 will then automatically downloaded, built and installed to the correct folder.

It is also possible to use vcpkg install irrlicht[fast-fpu] to build with fast math. If you need the Tools FontTool, GUIEditor, MeshConverter or FileToHeader, use vcpkg install irrlicht[tools]. The combination of both irrlicht[fast-fpu,tools] is possible too.

If this is tested well and works fine, ill consider creating a Pull Request to https://github.com/Microsoft/vcpkg/ so you dont need the steps 1 & 2

Thanks to Darktib for creating the CMakeLists.txt for Irrlicht. (http://irrlicht.sourceforge.net/forum/viewtopic.php?f=9&t=50774)