This adds two timeouts in total: one for sending begin, and getting
headers, and one for getting the rest of the data.
These timeouts are way too long right now, but at least the code is
there.
Some requests are still useful when we get only a partial response
-- like those where we're asking for a bunch of documents at once.
For those, we should return any nonempty partial result.
It can send a GET request on a circuit, get an answer, and
decompress it with zlib.
It will need documentation and tests eventually, as well as serious
refactoring.
Nick Mathewson
owen66