The `disable_logging` attribute was only available on events and
responses, and it could only either entirely disable or enable logging
for all the events of a certain type.
The new flag allows more customization by setting the default logging
level used for any message of a certain type (or `None` to disable
logging). This makes it possible to e.g. set some verbose events to
debug level, and the user can see them if they configure the application
in debug mode.
It also delegates the logging logic to the message itself, instead of
having different parts of the application handling their own logic.
Fabio Manganiello
d4b540dd67
