Make lattice volumes opaque. Closes #248.
Edges are now a different color than the faces.
Edges are now rendered before faces.
Renamed tranpsarency checkboxes.
Hooked up transparency check boxes.
Hooked up transparency for edges / faces.

Need to re-introduce ztest (transparently, probably) to avoid rendering
artifacts.
Reduced transparency of faces.
Removed ztest option and added GPU state management for passes.
Fixed typo.
Line width is now set in SCIRun instead of in statically in Spire.