XS interface completed, including new Line class

xs/xsp/Line.xsp

@@ -0,0 +1,30 @@
+%module{Slic3r::XS};
+
+%{
+#include <myinit.h>
+#include "Line.hpp"
+%}
+
+%name{Slic3r::Line} class Line {
+    ~Line();
+    Line* clone()
+        %code{% const char* CLASS = "Slic3r::Line"; RETVAL = new Line(*THIS); %};
+    SV* arrayref()
+        %code{% RETVAL = THIS->to_SV(); %};
+    SV* pp()
+        %code{% RETVAL = THIS->to_SV_pureperl(); %};
+    void reverse();
+%{
+
+Line*
+Line::new(...)
+    CODE:
+        RETVAL = new Line ();
+        // ST(0) is class name, ST(1) and ST(2) are endpoints
+        RETVAL->a.from_SV_check( ST(1) );
+        RETVAL->b.from_SV_check( ST(2) );
+    OUTPUT:
+        RETVAL
+
+%}
+};