The logger is now threaded into the query controller, executor, and the
dispatcher so that we can log panics. They are logged at the info level
because the panics do not result in the system crashing and becoming
unusable.
Introduces the Statisticser interface which ResultIterators may
implement.
The HTTP implementation uses HTTP trailers to preserve the statistics.
This way we do not need to have all encoders and decoders support
statistics.
It was effectively a copied and pasted platform.ID, so change it to a
type alias. Once our known references to the query/id package are
updated to platform.ID, we'll delete the package.
Jonathan A. Sternberg
Adam Perlin
Nathaniel Cook
Mark Rushakoff