Change PropertyExpression generics to match SkriptLang

[TheLimeGlass]

Change PropertyExpression generics to match SkriptLang. This drives me crazy when working with the skript-parser. In my opinion, it should match Skript's generic order like reading a book. Left to right. The left element gets the property return of the right element.

This is a big breaking change unfortunately.

I'll keep this updated as I will be cherry-picking this pull for my projects.