B"H view1090: handle disconnection

 - keep trying to reconnect to server if disconnected
B"H view1090: do not block

 - do not block on network data
B"H view1090: sleep a bit between loops

view1090 was using close to 100% CPU before, with the non-blocking
commits and the reconnection code. sleep a bit between loop iterations
to keep CPU usage low.

CPU usage with this addition was down to <1% in testing.
B"H view1090: do not use pthreads

It *seems* that pthreads are used in dump1090 for I/! sample reading
only. So view1090 need not use pthread_exit.
Update dump1090.c
Create convienience.h
Create convienience.c
Update dump1090.c
Update dump1090.c
Delete convienience.h
Delete convienience.c
Update dump1090.c
Merge pull request #22 from matthewbrandes/master

Allows choosing device by serial number rather than device index which can change.
Merge pull request #21 from hhm0/view1090_net_mods

View1090 net mods
B"H decoding: use last air position to calculate ground position
Merge pull request #23 from hhm0/decoding

use last recent airplane position to calculate its ground position
Version 1.09.1007.14

Updates to support COAA Planeplotter Ground Station on an RPi
Version 1.09.1607.14

Improvements to COAA MLAT functions
Reduce CPU load in PPUP1090 and DUMP1090 during cleanup
Tidy up interactive.c

Remove spaces from the end of line.
net_io port 30003 bug

Thanks to "Harrie" for this one.
Fix the SBS port 30003 stream to always include speed and/or heading
when available.