Merged support_fills with support_interface_fills.

When extruding supports, the support is interleaved with interface
if possible (when extruded with the same extruder).
Otherwise the base is extruded first.

xs/xsp/ExtrusionLoop.xsp

@@ -27,6 +27,8 @@
         %code{% THIS->clip_end(distance, &RETVAL); %};
     bool has_overhang_point(Point* point)
         %code{% RETVAL = THIS->has_overhang_point(*point); %};
+    ExtrusionRole role() const;
+    ExtrusionLoopRole loop_role() const;
     bool is_perimeter();
     bool is_infill();
     bool is_solid_infill();
@@ -46,16 +48,6 @@ ExtrusionLoop::arrayref()
     OUTPUT:
         RETVAL
 
-ExtrusionLoopRole
-ExtrusionLoop::role(...)
-    CODE:
-        if (items > 1) {
-            THIS->role = (ExtrusionLoopRole)SvUV(ST(1));
-        }
-        RETVAL = THIS->role;
-    OUTPUT:
-        RETVAL
-
 %}
 };