Adds support for URLs (streaming) in m3u playlist files.

Also added a few file types that the filescanner should ignore.

src/main.c

@@ -579,6 +579,7 @@ main(int argc, char **argv)
     }
 
   av_register_all();
+  avformat_network_init();
   av_log_set_callback(logger_ffmpeg);
 #if LIBAVFORMAT_VERSION_MAJOR < 53
   register_ffmpeg_evbuffer_url_protocol();
@@ -814,6 +815,7 @@ main(int argc, char **argv)
 
  signal_block_fail:
  gcrypt_init_fail:
+  avformat_network_deinit();
   av_lockmgr_register(NULL);
 
  ffmpeg_init_fail: