More compact Model sliders

[endersaka]

With this proposal #101 in mind, I was thinking of a more compact UI. And I came out with something like this.

The idea is to organize differently the components to present a UI that is already as compact as possible, not to exclude the options proposed in #101 and comments, so, on the same wavelength, I envision the ability to hide/collapse the thumbnails with a configuration option to walk alongside my proposal here.

Compact Model panel sliders