use empirically found threshold to speed up issubset by creating Set …#26198

Merged

JeffBezanson merged 2 commits intoJuliaLang:masterfrom twistedcubic:yd/issubsetOptimization

Mar 7, 2018

+10

Commits on Feb 25, 2018

actually resolving the merge conflict correctly
Yihe Dong
committed

Commits on Feb 28, 2018

update Set to AbstractSet to cover all Sets, per Jeff's suggestion
Yihe Dong
committed