Implemented the majority of new features.  Added constants for setting location of fields in binary telemetry message.  Added struct for telemetry message.  Added Mavlink fields.  Added circular buffer to handle inbound MAVlink message.  Added 512 byte buffer for transmit.  Added USART0 Rx interrupt to handle MAVlink message.  Added USART1 Tx interrupt to handle transmitting telemetry message.  Implemented message buffer initialization.  Switched serial setup to register writes.  Added USART1 setup.  Added timer interrupt setup.  Added MAVlink protocol handling.  Added ADC reads, spaced to prevent 13 us blocking.  Added logic for writing telemetry message struct to binary form for transmit.  Added start transmit logic.