[Request] Ability upgrade tooltips

[Tonyleila]

I see myself always looking into Esohead to find out what to skill next. Often a skill is not very good but when you upgrade its super powerfull. Also you may have already upgraded a skill and want to know what other upgrade was possible or what the name of the base skill was. Woud be great to see it in tooltips next to the original spell tooltip in the book. Thanks for reading!