Polish and fixes. Now the totally-already-existing item component works to control the kaleidoscope's view texture, and it's post-effect!
You can access this with /give @s kaleidoscopes:kaleidoscope_item[kaleidoscopes:kaleidoscope_overlay={texture:TEXTURE,post_effect:POST_EFFECT}]
No longer crashes the server on startup.
(almost) all assets are working now! Wooooo. yay.
Added icon, bumped version
This time it DOESN'T crash the server.
One fewer bug. Hooray!