Cleaned up serial port libs, activated mav visualization on map (still debugging), fixed standalone MAVLink generator

The MAVLINK_MESSAGE_LENGTHS macro can be used to detect mavlink
messages that don't have the expected length. It is done as a macro so
that projects that don't want to pay the cost of a 256 byte overhead
can avoid the check

Set to 38400,8,N,1 just need to map the baud rate enums now.