Added the ASSIMP library

Added the files provided for the tutorial
Added the SplitMeshNode and SubMeshNode classes

Assimp/include/assimp/Compiler/pushpack1.h

@@ -0,0 +1,43 @@
+
+
+// ===============================================================================
+// May be included multiple times - sets structure packing to 1 
+// for all supported compilers. #include <poppack1.h> reverts the changes.
+//
+// Currently this works on the following compilers:
+// MSVC 7,8,9
+// GCC
+// BORLAND (complains about 'pack state changed but not reverted', but works)
+// Clang
+//
+//
+// USAGE:
+//
+// struct StructToBePacked {
+// } PACK_STRUCT;
+//
+// ===============================================================================
+
+#ifdef AI_PUSHPACK_IS_DEFINED
+#	error poppack1.h must be included after pushpack1.h
+#endif
+
+#if defined(_MSC_VER) ||  defined(__BORLANDC__) ||	defined (__BCPLUSPLUS__)
+#	pragma pack(push,1)
+#	define PACK_STRUCT
+#elif defined( __GNUC__ )
+#	if !defined(HOST_MINGW)
+#		define PACK_STRUCT	__attribute__((__packed__))
+#	else
+#		define PACK_STRUCT	__attribute__((gcc_struct, __packed__))
+#	endif
+#else
+#	error Compiler not supported
+#endif
+
+#if defined(_MSC_VER)
+// C4103: Packing was changed after the inclusion of the header, probably missing #pragma pop
+#	pragma warning (disable : 4103) 
+#endif
+
+#define AI_PUSHPACK_IS_DEFINED