Rename types to eltypes
Merge pull request #539 from garborg/eltypes

Rename types to eltypes
Update doc, make sure examples work
Merge pull request #541 from JuliaStats/doc

Update doc, make sure examples work
Make cross joins handle naming collisions
Merge pull request #542 from JuliaStats/crossjoin

Make cross joins handle naming collisions
Fix for Set constructor changes (JuliaLang/julia#5897)