Introduce PRIappid printf specifier for mstro_app_id

include/maestro/core.h

@@ -43,6 +43,7 @@ extern "C" {
   #include "maestro/config.h"
   #include "maestro/status.h"
   #include <stdint.h>
+  #include <inttypes.h>
   
   /**@defgroup MSTRO_Core Maestro Core API
    **@{
@@ -97,6 +98,11 @@ extern "C" {
    **/
   typedef uint64_t mstro_app_id;
 
+  /**
+   ** A printf format specifie suitable to print an @ref mstro_app_id value
+   **/
+  #define PRIappid PRIu64
+
   /**@} (end of group MSTRO_Core) */
   
   /* include the remaining public API */