GitLab

* feat(porep): update API for interactive PoRep

* fix(build): grab .pc file from appropriate location

* fix(leak): point to patched sector builder

* feat(workers): configurable number worker threads

* fix(leak): point to patched sector builder

* fix(lint): use proper error formatter

* tidy

* fix(opencl): install opencl

* fix(cache): v15 cache

Interactive PoRep will split the existing seal operation into a
two-step flow. In the first step, the pre-commit operation will persist
some artifacts to a per-sector directory (a subdirectory of the
sector cache root-dir) for the commit operation to load.

Closes #2 

- sector id is now a uint64
- generate_post accepts faults instead of producing them
- generate_post produces a single proof instead of a concatenation of proofs
- verify_post accepts a single proof

feat(stub piece expiry UTC seconds argument)

feat(add basic build)