Simpit V2.1.0

Features

Add a generic parseMessage function (in the Arduino lib)
Add message for atmospheric conditions
Add the Comnet control level, current stage, a boolean to indicate if a target is set and current vessel type in a FlightStatus message
Change internal way to handle some messages. In particular prevent sending a message if no information has changed for some channels. This is applied to ressources messages and FlightStatusMessage for now.
Add a message with information about current vessel rotation, its velocity orientation, maneuver and target orientation (change in maneuver and target message).
Add a message to control custom axis.
Add a message to close the connection from the Arduino.

Bugfixes

Fix an issue where the messages to control throttle did not work for parts assigned to main throttle.
Fix a typo in FlightStatus helper functions