Fix missing include.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@2857 dfc29bdd-3216-0410-991c-e03cc46cb475

include/IMeshManipulator.h

@@ -10,6 +10,7 @@
 #include "aabbox3d.h"
 #include "matrix4.h"
 #include "IAnimatedMesh.h"
+#include "IMeshBuffer.h"
 #include "SVertexManipulator.h"
 
 namespace irr
@@ -17,8 +18,6 @@ namespace irr
 namespace scene
 {
 
-	class IMesh;
-	class IMeshBuffer;
 	struct SMesh;
 
 	//! An interface for easy manipulation of meshes.