* main,bind,_examples: fix tests for go 1.16
This CL fixes a number of tests that are failing under go 1.16.
Modules behave a bit differently, the //comment directives now
need a space, generated version file needs go fmt, and there was a
mis-named symbol
* ci: Update travis and appveyor for recent Go and fix pypy download links
* ci: fix typo in travis script, and adjust go to max appveyor version
* ci: update appveyor PATH to pick up proper latest go version
* fix: Re-enable test cleanup
* ci: update appveyor to pin GOROOT
* ci: update appveyor to use latest windows image