Back from the dead; now works with Polytone!

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Changelog:

• Added support for Polytone!
  You can now use either Polytone or Translucent Glass! I may make a vanilla version in the future if any of these mods don't update.

• Updated the pack.mcmeta to support 1.21.8.
  The resource pack works perfectly fine on 1.21.9-1.21.10, but due to how the new pack formatting works, I can only define "support" for either 1.20.2-1.21.8, or 1.21.9-1.21.10. Once 1.22 comes out, I'll be switching to the new pack formatting.
  

• Updated the credits file.
• Updated the license file (the license itself didn't change).
• Updated the pack.png to cleaner, better render of the glass block.
• Updated the pack.mcmeta description to be consistant with my more recent projects.
• Tweaked the colors for most of the Stained Glass textures.
• Slightly reduced the opacity of normal Glass, and Tinted Glass