Katcp

* All params in `future_get_sensor` are now cast to byte strings (PR [235](https://github.com/ska-sa/katcp-python/pull/235)).
* Added tests to`test_fake_clients.py` and `test_inspecting_client.py` (PR [235](https://github.com/ska-sa/katcp-python/pull/235)).
* Ensure testutils method casts expected requests to byte strings (PR [233](https://github.com/ska-sa/katcp-python/pull/233)).

* Added Python 3 compatibility (PR [215](https://github.com/ska-sa/katcp-python/pull/215))

* Fix some client memory leaks, and add `until_stopped` methods (PR 206).
* Increase server's MAX_QUEUE_SIZE from 30 to 300 to handle more simultaneous
client connections (PR 208).
* Use correct ioloop for client AsyncEvent objects (PR 210).

* Put docs on readthedocs (PR 192).
* Added error handling when parsing Message arguments that include non-ASCII
characters (not following KATCP specification). Invalid characters are replaced
with question marks, possibly breaking functionality (PR 193).
* Increase container sync time from 8 sec to 20 sec, and initial resync
timeout from 1 sec to 5 sec, to better support large containers (PR 194).
* Limit tornado version to <5 because the openssl version on Ubuntu 14.04
is not compatible (PR 195).
* Allow sampling strategy to be removed from cache, to better support clients
working with devices that dynamically remove sensors (PR 196).
* Provide a meaningful error message for the DeviceMetaClass assert statements
(PR 198).
* Increase server's MAX_QUEUE_SIZE from 30 to 300 to handle more simultaneous
client connections (PR 199). (Not in release 0.6.3 - it was only on the
release/karoocamv20 branch)
* Updates to Jenkinsfile for pipeline improvements (PR 200, 201, 202).
* Add information on how to contribute to the project (PR 203).

* Bumped the tornado dependency to at least 4.3
* Started work to support for python3 (not production ready)
* Added the ability to let ClientGroup wait for a quorum of clients
Give ClientGroup.wait() the ability to wait until a subset of clients
(a 'quorum') satisfy a sensor condition.
* Added an until_some helper function
* Added timeout hints usage to the resource client
* Added default request-timeout-hint implementation to server.py
It is only activated if the server protocol is set to the (proposed) KATCP v5.1
spec and the timeout hint protocol flag is enabled.
* Moved IOLoopThreadWrapper to ioloop_manager.py, a more sensible location
* Improved unit test coverage and implementation in some cases
* Started work on implementing an async device handler
* Numerous docstring and code style improvements throughout
* Fixed a bug where the timeout parameter was not passed down in until_state()
* Fixed a bug where model updates were never sent by the inspecting client
callback when sensor sync failed
* Changed the __str__ method for InspectingClientStateType to be more compact
* Added a random-exponential retry backoff process to the inspecting client,
to ensure that the thundering herd does not continue thundering
* Properly handle errors during inspection in inspecting client
* Added support for continuous integration using a Jenkinsfile

* Increased the maximum message size that can be received up from 128k to 2M
* Minor docstring fixes
* Fixed testutils
* Fixed inspecting client from losing units values
* Avoid blocking python interpreter shutdown and avoid leaking file descriptors
* Improved setup.py dependencies and removed pip-build-requirements.txt
* Allow high level clients to preset KATCP flags
* Simplify sensor wait() interface
* Added a check that the sensor exists before removing it
* Better handling of malformed log lines
* Use katversion and git tags to determine package version on install

15 June 2016 (0.6.0)
* Added high level, simple to use, client API (KATCPResource) that connects to,
inspects and presents a high level, hierarchical object oriented interface to
multiple KATCP devices.
* Added mid level client API (InspectingClient) that abstracts the inspection
of a KATCP device.
* Backwards-incompatible change in Sensor observer API
* Sensor strategies now call back with raw Python datatype values rather than
KATCP formatted values, using the same 'reading' API as Sensor
observers' update methods.
* Tornado ioloop / iostream based sensor sampling
* Tornado ioloop / iostream based server
* Sever message handlers can now return futures
* Server supports fully async mode with Tornado futures.
* Threaded message handle compatibility mode + new Async mode (performance
penalty for threaded mode, but is default for now)
* Tornado ioloop / iostream based client AsyncClient, single implementation for
both BlockingClient and CallbackClient based on thin wrapper around
AsyncClient.
* Clients now stop much faster due to removal of 0.5s select timeout in
previous implementation.
* Backwards incompatible change in BlockingClient.blocking_request(): now
returns a failed reply rather than raising an exception for timeouts (like
CallbackClient.blocking_request() always did).
* Threadsafe mode (default for BlockingClient and CallbackClient) available, but
comes with performance overhead even async for usage.
* Hundreds of test-suite reliablility improvements.