The `partial` tag has been added to the JSON response of a series and
the result so that a client knows when more of the series or result will
be sent in a future JSON chunk.
This helps interactive clients who don't want to wait for all of the
data to know if it is done processing the current series or the current
result. Previously, the client had to guess if the next chunk would
refer to the same result or a new result and it had to match the name
and tags of the two series to know if they were the same series. Now,
the client just needs to check the `partial` field included with the
response to know if it should expect more.
Fixed `max-row-limit` so it counts rows instead of results and it
truncates the response when the `max-row-limit` is reached.