Ported (and used) ExtrusionPath->first_point

xs/xsp/ExtrusionPath.xsp

@@ -16,6 +16,8 @@
     void reverse();
     Lines lines()
         %code{% RETVAL = THIS->polyline.lines(); %};
+    Point* first_point()
+        %code{% const char* CLASS = "Slic3r::Point"; RETVAL = new Point(*(THIS->first_point())); %};
 %{
 
 ExtrusionPath*