Fix for Editor (Padishar)

Change OnUpdate to Update
Update readme. V3.0 FINAL
Fixed; v3.0.1 FINAL

Fixed my stupidity; when I converted from OnUpdate to Update, I left
base.OnUpdate, and I reran UpdateCrossfeed every frame. Both issues
fixed. Also cleaned up some logic and no longer test Contains() before
doing Remove() (2n->n performance)
v3.0.1 FINAL-FINAL (readme update)