Update the End Crystal Recipe to Include Amethyst

https://i.imgur.com/KSc1YtE.png

I propose that amethyst (not glass) should be used to build the end crystals, I think glass is much to mundane for such a mystical item, and that the new amethyst item really fits the end crystals with it being crystal, purple, and having strange properties with light which jibes with the beams the crystals produces.