Needed: More Themes!

[Jaremy Creechley]

I've only done a very basic theme or two. The Bulma one doesn't look quite right.

The current themes are here: https://github.com/elcritch/fidgetty/blob/main/src/fidgetty/themes.nim

Here's the API for theming:

https://github.com/elcritch/fidgetty/blob/main/src/fidgetty/theming.nim