add Steven Universe palettes / themes

Ryo-N7

Garnet, Amethyst, ... and Pearl ... AND STEVEN!

Comments

Ryo-N7

hmm... i ended up creating 32 (THIRTY TWO) different palettes 2 years ago!

- [ ] need to add the proper example image in README - [ ] need to add proper examples in Examples vignette - [x] take out glue dep: replace readme plot with ~~static imgur link~~ save as local file (keep the glue in the code because you need that to actually render the emoji), take out the glue deps in the functions as you can just use paste0 - [x] create tests