Fix typo.

src/mtime_timedelta.c

@@ -1320,7 +1320,7 @@ getTimeDeltaFromDateTime(struct _datetime* dt1, struct _datetime* dt2, struct _t
   struct _julianday jd2;
   date2julian(dt2, &jd2);
 
-  /* Calculat Delta on Julian axis. "RULE: A - B = Delta". If A > B, Delta is positive. */
+  /* Calculate Delta on Julian axis. "RULE: A - B = Delta". If A > B, Delta is positive. */
   struct _juliandelta jd;
 
   /* Substract the 2 dates on julian axis. */