added 3 commits

Fix  missing variables in printf statments
Fix subscriptioncount not decreasing
Fix SSEBroadcastState (argument sequence wrong)

Address points of @devyte's code review:
* Use IPAddress vs. uint32_t
* Refactor the URL parsing logic to use strlen vs. sizeof, since there
  was some confusion in the original (correct) version
* Minimize copies of WiFiClients while in use
* Use byref access for sensor updates

Fix multi-sensor updates
* Create an update Ticker for each sensor, because the original code
  only had one whose callback was overridden by sensorB, meaning sensorA
  never changed