v0.4.1

Internal features:

• add and expose core/hooks feature to plugin parts

Fixes:

• plugins/join: do not allow calling join() without channel
• plugins/reconnect: throw on connect without existing error listener
• plugins/verbose: stringify raw messages
• plugins/oper_on_register: restore missing test

Refactoring:

• core/client: preserve stack trace of thrown errors
• core/events: change visibility of resetErrorThrowingBehavior() and count()