message: friendly to c++ and add stdint
diff: # define CARDANO_RUST_H
  /* Basic Types */
  +#ifdef __cplusplus
  +extern "C" {
  +#endif
  +
  +#include <stdint.h>
  +
  typedef int cardano_result;
  /*********/
  @@ -68,4 +74,8 @@ cardano_staging_transaction *cardano_transaction_new(void);
  //cardano_transaction_add_input();
  //cardano_transaction_add_output();
  +#ifdef __cplusplus
  +}
  +#endif
  +
  #endif
  