cleanup: remove dead code, fix bugs, refactor SSH dest parsing

- Remove debug printf calls from file.c
- Remove dead code: chunk_print, chunk_format, chunk_data_create/delete
- Remove unused config.use_single_send_per_file field
- Fix server_delete() no-op (double-pointer)
- Fix double cast (long)(long) -> ptrdiff_t in chunk.c
- Fix thread return value: thrd_error instead of 1
- Remove unused config param from receive_chunk_enqueue()
- Make queue_double_capacity() static
- Move SSH dest parsing into config.c as config_parse_ssh_dest()
- Fix test_config_ssh_dest to test parsing round-trip
- Remove chunk_format test (obsolete format)
- Replace chunk_data_delete with data_destroy in tests

src/shared/config.h

@@ -17,7 +17,6 @@ typedef struct Config {
   bool use_chunk_serialization;
   bool use_compression;
   bool use_sendfile;
-  bool use_single_send_per_file;
   bool use_metadata;
   int compression_level;
   int num_connections;
@@ -33,5 +32,7 @@ Config *config_create(char *version, char *send_directory,
 void config_delete(Config *config);
 void config_send(int file_descriptor, Config *config);
 Config *config_receive(int file_descriptor);
+bool is_remote_dest(const char *s);
+void config_parse_ssh_dest(Config *config);
 
 #endif