From Alessandro Terenzi: modifications for supporting opacity, reflective and emissive maps beyond the already supported diffuse map in the FBX plugin.

A problem with transparency has also been fixed: objects were transparent wrt themselves but were opaque wrt to other objects.
Finally I added the support for "mixing factors" of diffuse, reflective and opacity textures/values.

From Michael Platings: added "LightmapTextures" plugin option that changes the way textures are interpreted so Alessandro's models appear correctly. Also refactored to put many functions in one class to avoid passing around too many arguments to functions.

src/osgPlugins/fbx/fbxRLight.cpp

@@ -7,9 +7,9 @@
 #endif
 #include <fbxsdk.h>
 
-#include "fbxRLight.h"
+#include "fbxReader.h"
 
-osgDB::ReaderWriter::ReadResult readFbxLight(KFbxNode* pNode, int& nLightCount)
+osgDB::ReaderWriter::ReadResult OsgFbxReader::readFbxLight(KFbxNode* pNode, int& nLightCount)
 {
     const KFbxLight* fbxLight = dynamic_cast<const KFbxLight*>(pNode->GetNodeAttribute());