Support superscripting in diagram titles

[jonthysell]

Add more title label options, including superscript

Original ask:

Here is my little proposal for a possible additional feature for future
Chordious releases: as you probably know, chord notation in jazz and
popular music, often makes use of superscripts to specify chord quality:
e.g. C#M7 can be found written as C#maj7, with only "7" rather than the
whole "maj7" superscripted. It would be great if Chordious allowed the
user to superscript the "trailing" part of any custom chord names
(titles) in the personal diagram library.