Adds initializer_list test for slice
Adds initializer_list test for slice

tempbottle/cppitertools,tempbottle/cppitertools,jkhoogland/cppitertools,ryanhaining/cppitertools,jkhoogland/cppitertools,tempbottle/cppitertools,jkhoogland/cppitertools,ryanhaining/cppitertools,ryanhaining/cppitertools