Add functions for querying and messaging master.
Slave_Q_Master() is a simple function that sends a query and receives a response. Slave_Msg_Master() is a simple function that sends a message to the master without a response.
Add comments to new functions.
Add comments to Slave_Q_Master(), Slave_Msg_Master(), and Master_Loop() to explain what they do, what the variables mean, and how they work.