Renamed the osgVolume::Layer/ImageDetails parameters RescaleIntercept and RescaleSlope to more general TexelOffset and TexelScale, and changed type to Vec4.

Refactored the transfer function set up in RayTracedTechnique to prepare for new scale and offset uniforms.

Updated wrappers

examples/osgvolume/osgvolume.cpp

@@ -1353,8 +1353,8 @@ int main( int argc, char **argv )
 
     if (details)
     {
-        layer->setRescaleIntercept(details->getRescaleIntercept());
-        layer->setRescaleSlope(details->getRescaleSlope());
+        layer->setTexelOffset(details->getTexelOffset());
+        layer->setTexelScale(details->getTexelScale());
     }
 
     switch(rescaleOperation)