Can't draw button w/o texture

[avivey]

There's code and comments about being able to draw a button with only text (https://github.com/blizzy78/ksp_toolbar/blob/master/Toolbar/Internal/Toolbar/Button.cs#L83), but it will never be visible - see https://github.com/blizzy78/ksp_toolbar/blob/master/Toolbar/Internal/Toolbar/Command.cs#L143

[blizzy78]

The Text property is currently unused, and I don't have plans to allow text buttons on the toolbar again. (They were text-only in a very early version.)