Retry strategy for flaky tests

c998673eb0/src/cowboy_stream_h.erl (L153-L157)

Sometimes the stacktrace is a larger array of {M, F, A, Prop} tuples.
The handler code was expecting at most 2 tuples in the list. Relax this
requirement and add a test that provokes this edge-case.

* Handle new gen_server crash messages that contain client pid and stacktrace
* Update platform define for OTP 20
* Handle arity change in gen_fsm handle_msg

Don't use dirty timeout for gen_statem

That was introduced in OTP 19.2, and causes
failures in tests on OTP 19 and 19.1

Fix statem for all 19.x releases

On final analysis, it appears the effective fix is clearing out leftover lager state in the application controller.
Along the way, the test body was modified to account for the runtime system, and as this doesn't seem like a bad thing it's left in place.

This commit also moves `otp_version/0` to `lager_util`'s public API, as it may be helpful in future tests that check for version-specific messages (see issue #383).

This allows users to log metadata (tuple list) without a format string in lager. For
example `lager:info([{foo, bar}])` instead of `lager:info([{foo,bar}], "")`.

Lager logs its own application start up message. Previously
this message was discarded or not received quickly enough
to cause test failures, but now it seems as though it
is being received and causing several test failures
even though we are explicitly flushing it away.

We introduce a 5 millisecond sleep for several tests
to make sure the start up message is received before the
flush command dumps it.

Lager logs its own application start up message. Previously
this message was discarded or not received quickly enough
to cause test failures, but now it seems as though it
is being received and causing several test failures
even though we are explicitly flushing it away.

We introduce a 5 millisecond sleep for several tests
to make sure the start up message is received before the
flush command dumps it.

The sync_error_logger file looks up the value to send from a process
dictionary entry named `warning_map' When it is unset, it uses a mapping
which is fine for OTP 17 and before, but 18 and 19 the value changed.

So now we put the current mapping value into the process dictionary so
that the messages do not cause failed tests.

During code review we decided that using Sink ++ '_lager_event'
would provide better isolation for gen_event names than
Sink ++ '_event' as we had been using up to this point.

For example a sink called 'audit' is now 'audit_lager_event'
than 'audit_event' which might clash with a user's predefined
own module or process name.

Previously, would fail due to lager:get_loglevel/2 not being exported.

Previously all messages were being flushed, which meant that trapped exits
and internal gen_event messaging was also flushed, leading to undefined
behaviour.

closes #198

Adds transparent event stream processing and statistics.
A new 3-tuple trace is introduced as `{Key, Op, Value}`, but
for backwards compatibility `{Key, Val}` implies `=` for `Op`
and `{Key, '*'}` remains as is in the case of wildcards.
A simplified query tree module is generated which reduces
redundant selection conditions to minimize filtering overhead.