implicit arguments in quotient.v, close #447
make setrel notation global is_mere_relation in Overture
remove unnecessary Let in Quotient module
oops
coqdoc
Remove a useless match

Discovered as useless due to a bug in Coq trunk:
https://coq.inria.fr/bugs/show_bug.cgi?id=3561
Merge pull request #450 from mikeshulman/quotient

implicit arguments in quotient.v, close #447
Merge pull request #452 from JasonGross/remove-useless-match

Remove a useless match