ported optics.isph and shapesampler.isph to tutorial06
added support for multiple materials in tutorial06
added support for metal material to tutorial06
started to add xml parsing to tutorials
bugfix in solution file, AVX2 path was not selected properly under windows
Merge branch 'v2.3.2' into devel
Merge branch 'devel'
Merge branch 'master' of https://github.com/embree/embree