Implement error messages in the decoder side.

Update issue 7
Status: Started

tests/test_decode1.c

@@ -69,7 +69,7 @@ int main()
     /* Decode and print out the stuff */
     if (!print_person(&stream))
     {
-        printf("Parsing failed.\n");
+        printf("Parsing failed: %s\n", PB_GET_ERROR(&stream));
         return 1;
     } else {
         return 0;

tests/test_decode2.c

@@ -82,7 +82,7 @@ int main()
     pb_istream_t stream = {&callback, stdin, 10000};
     if (!print_person(&stream))
     {
-        printf("Parsing failed.\n");
+        printf("Parsing failed: %s\n", PB_GET_ERROR(&stream));
         return 1;
     } else {
         return 0;

tests/test_decode3.c

@@ -89,7 +89,7 @@ int main()
     /* Decode and print out the stuff */
     if (!check_alltypes(&stream))
     {
-        printf("Parsing failed.\n");
+        printf("Parsing failed: %s\n", PB_GET_ERROR(&stream));
         return 1;
     } else {
         return 0;

tests/test_missing_fields.c

@@ -27,7 +27,7 @@ int main()
         
         if (!pb_decode(&stream, MissingField_fields, &msg))
         {
-            printf("Decode failed.\n");
+            printf("Decode failed: %s\n", PB_GET_ERROR(&stream));
             return 2;
         }
     }