made tile simplier

tile.c

@@ -39,10 +39,7 @@ tile(void) {
 
 	nx = wax;
 	ny = way;
-	for(i = 0, c = clients; c; c = c->next)
-		if(isvisible(c)) {
-			if(c->isfloating)
-				continue;
+	for(i = 0, c = nexttiled(clients); c; c = nexttiled(c->next)) {
 		c->ismax = False;
 		if(i == 0) { /* master */
 			nw = mw - 2 * c->border;