fix: Small improvements

[vonagam]

Small types and consistency style fixes. But also one real fix:

handleConnection method of AuthenticationBase and JWTStrategy was never called in response to disconnect event, so when a jwt expiration timer emitted disconnect connection.authentication was not removed and the timer was not cleared. Added listener for disconnect event to fix this. Also added expirationTimers.delete after a timer is cleared and lt.clearTimeout before a timer is set (to ensure that only one timer per connection exist at a time, otherwise multiple calls to reAuthenticate with force can create more than one timer).

[daffl]

That makes sense, thanks! I thought this was being tested but I guess the test only covered that the authentication information had been removed.