Fixed in ackqueue_delete(): set new ackqueue_tail value if deleted last packet in the queue.
Fixed in central station: when answering to hello, set timestamp value in response packet.
Fixed in UAVStation: timestamps in DCP packet in millisecs.
Added handler for command setSessId and command_sessid member in uavsrv structure.
Added Disconnect handler.
Fixed Doxygen comments for handlers setSessId and helloFromCentral.
Added handler for packet isAlive.
Set handlers isalive,disconnect,setsessid ready when drone is registered.
Added sessid check in handler_setsessid.
Added sessid check in handler_disconnect.
Added sessid check in handler_isalive.
Added error UAVSRV_ERR_BAD_SESSID.
Added error UAVSRV_ERR_BADDATALEN.
Added datalen check in handler_hellofromcentral.
Added datalen check in handler_setsessid.