This commit was originally from @fredfishgames, but it
needed a big rebase due to use letting it sit too long.
Also, we decided not to have shebangs at the top of test
files.
Note that we now only have one conversation, since the case
of sending to streams has the same mechanics as sending PMs.
We'll eventually want a separate test to drive out differences
in the actual mechanics of the reply.
With this change, StateHandler.put() does only accept JSON-able
objects by default. The incrementor test tried to store the return
value of send_reply(), a non-JSON-able MockObject, in the state.
Therefore, this commits also sets functional default test return
values for send_message() and send_reply().
Finally, it fixes the tictactoe bot which relied on directly
modifying the state_ attribute.
This simplifies testing stateful bots by integrating the StateHandler
into the test library. As a side-effect, the mock bot handler gets
reused during a test, making the tests more realistic. The
StateHandler now keeps its state during a call to check_expected_responses,
forcing some stateful tests to be more verbose and explicit.
doc.md better describes the style of documentation that will live
inside these files, since we want these to be similar to our
webhooks' doc.md files in terms of how these are rendered and
composed of Markdown macros.
