Design new button system for inner views/controllers

A new button system, entirely controlled by adding appropriate classes to <a href>, <button> or <input type="button/submit">.

Icons should cover a broad variety of metaphors (e.g. metaphors already used in toolbar + footer plus more).
Should also cover display variants: Icon only, Icon + text, mini and maxi versions.

These buttons are only to be used within inner views and view controller dropdowns. The vertical toolbar uses its own (already existing) button style.