Fixed crash at exit if no stats file is specified
Removed alpha offset parameter. It makes no sense to allow triangles to have negative alpha/color values...
Added bonus: removing it doubles the convergence speed *and* improves long-term convergence PSNR!
Minor simplifications
Removed alpha field from triangles. It's pointless.
Moved color clipping from addtriangle()/scoretriangle() to run(), so that clipped values make it into the global triangle list.
README updates