Add proper management of stored messages to support persistent Store objects.
Add proper management of stored messages to support persistent Store
objects.

 - Changed stream reading mechanism to avoid overhead when reading a stream.
 - Added reading start condition to avoid reading all the stream in  case a reconnection is taking place and is not done.
 - Added stream destruction in case of disconnection.

bqevin/MQTT.js,jaambee/MQTT.js,AdySan/MQTT.js,RangerMauve/MQTT.js,wesley1001/MQTT.js,mcanthony/MQTT.js,itavy/MQTT.js,jdiamond/MQTT.js