Add more ui-elements

[Zweistein2]

Heyho,

it would be great if there could be more ui-elements like

• dropdownmenus
• radiobuttons
• checkboxes
• lists
• toggles
• sliders
• list boxes

and so on. More examples here

[tomcashman]

These would be good to add. The important thing is that each control works responsively both visually and input-wise. Considering this I don't know if a dropdown menu would work well for controllers as it would complicate the navigation implementations. So I would probably defer this until a later release.

A list box would be easily implemented using the ScrollBox and a button styling so this could be implemented as a utility class like TextButton.

Toggles would be a different rendering of a Checkbox.

So I think the following would be the only new base classes required:

• RadioButton (55c9969)
• Checkbox (a2b3607)
• Slider (e05d303)
• List