paho/session/state/initSession issues

[MattBrittan]

Describe the bug

Spotted two issues; logging them so they are not forgotten:

• Unnecessary call to ids, err = s.serverStore.List().
• inFlight := uint16(len(s.clientPackets)) will always be 0 because s.clientPackets is created at the top of the function and not populated.

The second issue is the result of a lot of edits in this area to try and find the best approach (s.clientPackets is now populated as the packets are resent to avoid the need to retrieve the packets multiple times). a bit of refactoring will be needed to handle this (would be good to find a way to properly handle changes to recvMax whilst addressing this issue).

Software used:

@master 27c89b5450f2bec03b2c1ee6e058f5e38f44e657

[MattBrittan]

These were both resolved in #180