Overhaul piaware connection management

* completely reworked how we know what's serving on port 30005 and 10001
 by using netstat to see what's listening.  This allows modesmixer2 or
 other programs to supply data without piaware getting confused.

* piaware now drops and reconnects its local ADS-B data connection if nothing
 is received after a timeout interval.

* once an "alive" message has been received from the server, expect them and
timeout and disconnect if they are not received after a decent interval

* ignore malformed messages from server

* piaware-config now only saves the config if something has changed

* ignore unrecognized messages from server

* many functions renamed to reflect changes in how we are doing things

* piaware-status now identifies what programs are serving ADS-B data

* enhanced logging messages

* Many new comments