Do not assume that days always have 86400 seconds

Make that date membership is computed correctly, even if a day has less
than 86400 seconds (e.g. after changing clocks).

Reported-by: Hakan Jerning <jerning@home.se>
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

src/apoint.c

@@ -119,8 +119,7 @@ struct apoint *apoint_new(char *mesg, char *note, long start, long dur,
 
 unsigned apoint_inday(struct apoint *i, long *start)
 {
-	return (i->start <= *start + DAYINSEC
-		&& i->start + i->dur > *start);
+	return (date_cmp_day(i->start, *start) == 0);
 }
 
 void apoint_sec2str(struct apoint *o, long day, char *start, char *end)