raop: Add autoreconnect feature

This patch adds the autoreconnect feature to the raop module.
This is mainly to be used in a server context, but can be used
also in a desktop usage context.

With autoreconnect feature, the raop module behaves like this:

- At initialisation or in case of the RTSP TCP connection lost, it
  tries to reconnect every 5 seconds
- In case of any fatal error, it tries to reconnect every 5 seconds
- In UDP mode, if no timing packets received anymore for a long time,
  RTSP connection is closed, then it tries to reconnect..
- After reconnection, once RTSP session has been established again,
  playing is resumed automatically.
- When the connection is not established yet (or loss), the sink
  behaves like a null sink. In the source code I called it "autonull",
  even if autonull is set to autoreconnect param value, it could be
  split into two different params.

src/modules/raop/raop-client.h

@@ -57,7 +57,7 @@ typedef enum pa_raop_state {
 } pa_raop_state_t;
 
 pa_raop_client* pa_raop_client_new(pa_core *core, const char *host, pa_raop_protocol_t protocol,
-                                   pa_raop_encryption_t encryption, pa_raop_codec_t codec);
+                                   pa_raop_encryption_t encryption, pa_raop_codec_t codec, bool autoreconnect);
 void pa_raop_client_free(pa_raop_client *c);
 
 int pa_raop_client_authenticate(pa_raop_client *c, const char *password);
@@ -71,9 +71,11 @@ int pa_raop_client_stream(pa_raop_client *c);
 int pa_raop_client_set_volume(pa_raop_client *c, pa_volume_t volume);
 int pa_raop_client_flush(pa_raop_client *c);
 int pa_raop_client_teardown(pa_raop_client *c);
+void pa_raop_client_disconnect(pa_raop_client *c);
 
 void pa_raop_client_get_frames_per_block(pa_raop_client *c, size_t *size);
 bool pa_raop_client_register_pollfd(pa_raop_client *c, pa_rtpoll *poll, pa_rtpoll_item **poll_item);
+bool pa_raop_client_is_timing_fd(pa_raop_client *c, const int fd);
 pa_volume_t pa_raop_client_adjust_volume(pa_raop_client *c, pa_volume_t volume);
 void pa_raop_client_handle_oob_packet(pa_raop_client *c, const int fd, const uint8_t packet[], ssize_t size);
 ssize_t pa_raop_client_send_audio_packet(pa_raop_client *c, pa_memchunk *block, size_t offset);