- Added PowerScaling to RenderableVolumeGL and RenderableFieldlines
- Removed the use of volumeraycasterbox since it used FBO and textures
which was not used anymore.
- Added a simple box implementation to RenderableVolumeGL that can have
PowerScaled vertex positions
TODO: The #include command needs to be extended in some way since the
FieldLines passthrough shader can't access the PowerScaled includes in a
good way.