and determine these dynamically if only one or the other is
specified but both are running on the same host

may cause inter-language confusion.

- end2end test deadlines may complete before checking IsCancelled
  => don't expect it to be false in these cases
- add exponential backoff to port_posix
- ensure run_tests rebuilds targets with a regex I commonly use

'TestService' in test.proto

machine if desired. The core_list flags to qps_driver are comma-separated lists of
core numbers.

- make the directory structure match the package structure
- sanitize the package structure (test --> testing)
- add auto-detection of proto file dependencies