Glowstone Spawning Revamp

I think that now the nether has been revamped, the random, scattered clusters of glowstone aren't up to the new aesthetic standards. They just look out-of-place, especially in basalt deltas.

You should revamp the generation of glowstone. Glowstone should still spawn on the nether ceiling, as the nerd-polling to get it is an interesting challenge. I would like it to spawn in large, ~15-block-long glowstone crystals.