splitting already-split idempotents
an endomap splits through at most one type
recovering the witness of idempotency from the splitting
the type of retractions is a retract of partially-coherent idempotents
big reworking of Idempotents
cbn works where simpl fails
Auto-update HoTT opam Coq version
Ooops, I forgot to update the allow-failures.
Fix for travis for when the depgraphs don't change
Merge pull request #653 from JasonGross/update-opam

Auto-Update opam
Don't leak the OAUTH token
Use a token with push bits for opam
Fix a typo in a travis error message
Fix OAUTH_TOKEN
Don't exit fatally if opam is up to date
Update OAUTH token for security
complete the proof of contr_from_Empty
Improve comments in Idempotents
Merge pull request #655 from mikeshulman/contr-from-empty

complete the proof of contr_from_Empty
Merge pull request #651 from mikeshulman/more-idempotents

More idempotents