Change New Tai Lue shaping engine from SEA to default

This is to reflect the UTC decision to change the encoding model of
New Tai Lue from logical to visual to be similar to Thai, Lao, and
Tai Viet: http://www.unicode.org/L2/L2014/14250.htm#141-C26

The visual encoding is already the current practice of encoding New
Tai Lue on the web anyway:
http://www.unicode.org/L2/L2014/14195-newtailue.txt

Fixes behdad/harfbuzz#66.

src/hb-ot-shape-complex-private.hh

@@ -259,6 +259,7 @@ hb_ot_shape_complex_categorize (const hb_ot_shape_planner_t *planner)
 
     /* Unicode-4.1 additions */
     case HB_SCRIPT_KHAROSHTHI:
+    case HB_SCRIPT_NEW_TAI_LUE:
     case HB_SCRIPT_SYLOTI_NAGRI:
 
     /* Unicode-5.1 additions */
@@ -339,7 +340,6 @@ hb_ot_shape_complex_categorize (const hb_ot_shape_planner_t *planner)
 
     /* Unicode-4.1 additions */
     case HB_SCRIPT_BUGINESE:
-    case HB_SCRIPT_NEW_TAI_LUE:
 
     /* Unicode-5.1 additions */
     case HB_SCRIPT_CHAM: