Add support for subscript and superscript in suffixes and prefixes

[spencerv]

Add support for subscript and superscript in suffixes and prefixes. This makes it clearer when inputting measurements such as metres cubed (like in the screenshots) or maths notation.

[garrett]

Hi @spencerv! You should be able to use unicode superscript characters for this: m³

[spencerv]

This works for some of the more basic ones but not all, particularly when working with different variable notation.