message: Fix missprint in C headers, formatting.
diff: @@ -133,7 +133,7 @@ extern sovrin_error_t sovrin_agent_listen(sovrin_handle_t command_handle,
  /// - xcommand_handle: command handle to map callback to caller context.
  /// - err: Error code
  -extern sovrin_error_t sovrin_agent_listen(sovrin_handle_t command_handle,
  +extern sovrin_error_t sovrin_agent_add_identity(sovrin_handle_t command_handle,
  sovrin_handle_t listener_handle,
  sovrin_handle_t pool_handle,
  sovrin_handle_t wallet_handle,
  