Keystone 1.3.3

Afterimage's far zone now works with OptiFine shader packs.

A pack makes the game build chunk geometry in OptiFine's vertex layout (normal, mid texture coordinate, tangent and block id next to the vanilla fields). Until now the far zone only knew the vanilla layout: with a pack loaded it took no new copies and drew the old ones with the wrong pointers, and its depth clear made the pack treat the far zone as sky.

• Copies are taken and drawn in the layout the game is building in, through the pack's own arrays and pointers, so a pack lights the far zone like the terrain in front of it.
• The depth buffer is left alone while a pack is loaded.
• The disk cache stays in the vanilla layout and serves both: a pack's vertices are written without their extra fields and get them back when read, worked out from the quad itself.
• Switching a pack on or off starts the copies in memory over; the cache on disk stays valid.

Everything else is unchanged.