Initial work for G-code sender and more intensive usage of Boost

xs/xsp/GCodeSender.xsp

@@ -0,0 +1,17 @@
+%module{Slic3r::XS};
+
+#ifdef BOOST_LIBS
+
+%{
+#include <myinit.h>
+#include "libslic3r/GCodeSender.hpp"
+%}
+
+%name{Slic3r::GCode::Sender} class GCodeSender {
+    GCodeSender(std::string port, unsigned int baud_rate);
+    ~GCodeSender();
+    
+    void send(std::string s);
+};
+
+#endif