Correct summing of elements in reduced_k_range time average

Fixed an issue that had the reduced_k_range diagnostic output use the wrong number of elements to determine the time average.

Also fixed an issue that would have caused an issue with reduced_k_range, time averaged diurnal sampling

Fixed mom-ocean#28

diag_manager/diag_manager.F90

@@ -2496,7 +2496,7 @@ LOGICAL FUNCTION send_data_3d(diag_field_id, field, time, is_in, js_in, ks_in, &
                          DO j=f3, f4
                             DO i=f1, f2
                                IF ( field(i,j,k) /= missvalue ) THEN
-                                  output_fields(out_num)%count_0d = output_fields(out_num)%count_0d + weight1
+                                  output_fields(out_num)%count_0d(sample) = output_fields(out_num)%count_0d(sample) + weight1
                                   EXIT outer3
                                END IF
                             END DO
@@ -2688,7 +2688,7 @@ LOGICAL FUNCTION send_data_3d(diag_field_id, field, time, is_in, js_in, ks_in, &
              END IF ! if mask present
           END IF  !if mask_variant
 !$OMP CRITICAL
-          IF ( .NOT.need_compute )&
+          IF ( .NOT.need_compute .AND. .NOT.reduced_k_range )&
                & output_fields(out_num)%num_elements(sample) =&
                & output_fields(out_num)%num_elements(sample) + (ie-is+1)*(je-js+1)*(ke-ks+1)
           IF ( reduced_k_range ) &