Try to fix reconnection problems

[skadisch]

Callbacks of an old connection are sometimes executed, which causes weird behavior. This PR tries to fix this by assuring that the callbacks are only executed if they have been initiated by the active connection.

This is a simple and fast solution to the problem, yet probably not the most beautiful approach.

[hbTecAG]

Hello Can you create a release with this PR? For us, this has helped to achieve a more stable behaviour.

Thanks and greetings Reto

[PLCHome]

@hbTecAG @skadisch i need your name at npm