OpenGL light is being operated on, and also now relies upong the standard
osg::State handling of OpenGL modes to switch on the appropriate lights.
The previous static counter mechansim for the light number was causing a
redundent light to be created when the osg plugin created the first osg::Light
to use a prototype for other osg::Light's to be cloned from in the
.osg plugin execution.
The static count mechanism also prevent the lights modes being controlled
independantly from the setting of the light paramters themselves. This
meant that a light once created was global, and couldn't be turned off
locally via the OSG's support for OpenGL mode enabling/disabling. This
has been overcome with the new implementation, the user has complete
flexiblity of when and where to use the different lights at their
disposal.
