voa: drop message if destination doesn't match
voa: cleanup: init_audio is now what it says, not the hidden main
voa: add my/dest address to voa data structure, fix related checks

needs testing
voa: print usage on -h
voa: fix and test addressing (incl. bit-masking)
voa: print error when connection to AllNet fails
voa: remove allnet_voa_header, unnecessary
voa: print own/dest address on launch
voa: return non-0 on failure in main loop
voa: reorder struct
voa: prefix print string with 'voa: '
voa: don't check signature on stream packet

should only be done on handshake packets
voa: initial stream ciphering (w/ random keys)
voa: streamcipher: change hmac and counter size
voa: don't modify msize in check_signature; also fix typo
voa: new methods to create and send handshakes
voa: unambiguate error message
voa: handle new stream requests in handle_packet
voa: header refactoring
voa: send new request when running as sender/encoder