If font style Superscript is set to true, Subscript is set to false.
Likewise, setting Subscript to true sets Superscript to false.
Both of these are working as they should. However,
setting Superscript to false causes Subscript to be set to true,
and setting Subscript to false causes Superscript to be set to true.
I believe that is an error in both cases. This change fixes it.
There seem to be no existing tests for Font styles.
I added the tests necessary to validate this change.
I will put adding more on my to-do list.
ef997a0c8e