Implement WieldMeshSceneNode which improves wield mesh rendering

- Don't create and cache an extruded mesh for every (non-node) item.
  Instead use a single one per image resolution.

- For cubic nodes reuse a single wield mesh too

- Improve lighting of the wielded item

- Increase far value of wield mesh scene camera, fixes #1770

- Also includes some minor refactorings of Camera and GenericCAO.

src/mesh.h

@@ -22,7 +22,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "irrlichttypes_extrabloated.h"
 #include "nodedef.h"
-#include <string>
 
 /*
 	Create a new cube mesh.
@@ -33,16 +32,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 */
 scene::IAnimatedMesh* createCubeMesh(v3f scale);
 
-/*
-	Create a new extruded mesh from a texture.
-	Maximum bounding box is (+-scale.X/2, +-scale.Y/2, +-scale.Z).
-	Thickness is in Z direction.
-
-	The resulting mesh has 1 material which must be defined by the caller.
-*/
-scene::IAnimatedMesh* createExtrudedMesh(video::ITexture *texture,
-		video::IVideoDriver *driver, v3f scale);
-
 /*
 	Multiplies each vertex coordinate by the specified scaling factors
 	(componentwise vector multiplication).