* Fix warning that not including a cmake source or build dir will be a fatal error (it is now on newest CMakes)
* Fixes appveyor
* Travis uses CMake 3.9 for more than a year now
* Travis dropped sudo: false in December
* Dropping Sphinx 2
- clang7: Suppress self-assign warnings; fix missing virtual dtors
- pypy:
- Keep old version (newer stuff breaks)
- Pin packages to extra index for speed
- travis:
- Make docker explicit; remove docker if not needed
- Make commands more verbose (for debugging / repro)
- Make Ubuntu dist explicit per job
- Fix Windows
- Add names to travis
