(PDB-660) Enable event streaming and provide other streaming cleanups

This provides streaming for the events end-point, thus removing the need for
event-resource-limit setting as well.

Some other cleanups around streaming have been provided also:

* stream-json-results is better documented
* remove-all-environments/remove-environment has been moved into query to
  align with how it is used in src/
* Positioned in-thread transacted query inside produce-body to make it clear
* lots of cases of :use converted to :require
* streamed-query-result no longer returns a function, never really needed to.
  The code is somewhat simpler now.
* munge-result-rows for events has now been moved into query so there is only 1
  place where munging is performed. Same for resources.

Signed-off-by: Ken Barber <ken@bob.sh>
(PDB-660) Throw deprecation warning for 'event-query-limit' and fix a docstring

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #975 from kbarber/ticket/master/pdb-660-events-streaming

(PDB-660) Enable event streaming and provide other streaming cleanups