fix definition of WHom, close #597
fix notation for W-types
unmarked errata for bceb7ca
unmarked errata for f9e542b
Merge pull request #604 from mikeshulman/wtypes

fix notation for W-types, close #603
Merge pull request #605 from mikeshulman/whom

fix definition of WHom, close #597
Mark Errata (auto)
Merge branch 'master' of https://github.com/HoTT/book into parenthesis

sync with upstream