refactor improve types and simplified usage

[Redhawk18]

I removed the tuple that the function pointer had, because there was no reason to have it in first place. With that I changed the type of options to a slice &'a [T] making its so many more types can be passed into to widget at creation. Doing that I had to change the required impl's from ToString to Display.

Also I'm considering adding support if the enum has a default, having that default be automatically highlighted. lmk if that's a good idea

[genusistimelord]

looks good thank you. Originally we had to use Cow for some reason, that I simply can not remember =D or that over time rust itself fixed the issue on the backend.