Add set.{iter,ior,iand,isub,ixor} - #524

Feb 23, 2019

Add set.{iter,ior,iand,isub,ixor}#524
windelbouwman merged 2 commits into
RustPython:masterfrom
palaviv:Improve-set-5

Add set.{ior,iand,isub,ixor}