"everfree castle" should be aliased to "castle of the royal pony sisters"

everfree castle (73)-> castle of the royal pony sisters (140)
 
The Art of Equestria book calls it the “Castle of the Two Sisters” but that has already been aliased into “Castle of the Royal Pony Sisters.”

I don’t see an issue with the alias, if no one disagrees I’ll go ahead.

Done.