Add reverse style to formatting

[jcubic]

I have an idea for a new feature for jQuery Terminal

You should be able to echo:

[[r;;]message]

or

[[;red;]hello [[r;;]world]]

in the First example, it should display black text and gray background and in the second example, it should print hello in red color and world as red background.

• [x] It should work with nested formatting
• [x] It should work with CSS custom properties
• [x] There should be a way to use with XML formatting
• [x] Unit tests