soulsoiledit

neovim: use mini.base16 for colorscheme

16

Switches both the neovim and nixvim modules to use mini.base16. Closes #535

neovim: support mini.base16

1

[mini.base16](https://github.com/echasnovski/mini.base16) provides greater plugin support than base16-nvim & generally looks nicer IMO. It would be nice to be able to select which plugin system to be used, or switch entirely...

### Checklist before submitting an issue - [x] I have searched through the existing [closed and open issues](https://github.com/elkowar/eww/issues?q=is%3Aissue) for eww and made sure this is not a duplicate - [x]...