Add Hypercolor theme for Vim and move both themes under the colors directory

[deuxpi]

This is a Hypercolor variation of the current Vim theme, based on the difference between the two originals. I compared the result visually with VS Code and it seems pretty accurate, despite that Vim has much less specific syntax classes.

Both Vim themes are also moved under a colors directory. This allows some plug-in managers to use this repository directly. For example, with vim-plug, that would mean Plug 'theacodes/witchhazel' works automatically.

This is now my daily theme! Thanks! 💜

[theacodes]

This is awesome! If you're up for it, I'd love a few instructions for Vim users on how to install this, similar to what we have for the other editors. You can just reply here and I can handle adding them to the site. :)