Fidgetty Widget System: Rewrite

[elcritch]

P.S. I pushed some tweaks to the nimble file. Doing a `nimble install fidgetty` 
should update it now. If you've clone the repo you can do `git pull && nimble 
develop` or `git pull && nimble install -d` to update deps. Let me know if that 
works! I'd appreciate the help.