+ Re-Added "mmocoreskills" alongside "mmocoreskill" as valid inputs.
+ Added minor small visual features.

* Fixed advancements not being shown unless the player had it.(woops)

I'm aware versions pre-dating 1.13 may not support some items very well.
This is because mc itself didnt have most of the current names we now have.
The default item "feather" is 1 such item, however, you can use Fire or other items as display items.
Hoping to have an alternative asap!