Fix for shapeBaseImage lights to appear at muzzlePoint

This snipet will fix the ShapeBaseImage lights to appear at the image's muzzlePoint.

In shapeImage.cc, ShapeBase::registerLights, replace:

getRenderMountTransform(imageData->mountPoint,&posMat);

with:

getRenderImageTransform(imageData->mountPoint,imageData->muzzleNode,&posMat);

This tiny change, believe it or not, makes a noticable difference with my WeaponFireLight(muzzle flash). Maybe it will improve yours, too.