The timezone is now set per Logger instance and not statically, either via ->setTimezone or passed in the constructor. Calls to Logger::setTimezone should be converted.
Removed non-PSR-3 methods to add records, all the add* (e.g. addWarning)
methods as well as emerg, crit, err and warn.
HandlerInterface has been split off and two new interfaces now exist for
more granular controls: ProcessableHandlerInterface and
FormattableHandlerInterface. Handlers not extending AbstractHandler
should make sure to implement the relevant interfaces.
HandlerInterface now requires the close method to be implemented. This
only impacts you if you implement the interface yourself, but you can extend
the new Monolog\Handler\Handler base class.