Without this, Thermite errors at compilation time.

Given the large amount of templated classes in PolyVox perhaps we need some tests in PolyVox which compile classes like this to find errors like this earlier?

library/PolyVoxCore/include/Material.h

@@ -27,6 +27,8 @@ freely, subject to the following restrictions:
 #include "PolyVoxForwardDeclarations.h"
 #include "PolyVoxImpl/TypeDef.h"
 
+#include <cassert>
+
 namespace PolyVox
 {
 	///This class represents a voxel storing only a material.