Merged the C++ port of the GUI Tabs / OptionGroup / Option classes

by @YuSanka, thanks @lordofhyphens for the initial port
of the OptionGroup / Option.

xs/src/libslic3r/Polygon.hpp

@@ -24,6 +24,12 @@ public:
     explicit Polygon(const Points &points): MultiPoint(points) {}
     Polygon(const Polygon &other) : MultiPoint(other.points) {}
     Polygon(Polygon &&other) : MultiPoint(std::move(other.points)) {}
+	static Polygon new_scale(std::vector<Pointf> points) { 
+		Points int_points;
+		for (auto pt : points)
+			int_points.push_back(Point::new_scale(pt.x, pt.y));
+		return Polygon(int_points);
+	}
     Polygon& operator=(const Polygon &other) { points = other.points; return *this; }
     Polygon& operator=(Polygon &&other) { points = std::move(other.points); return *this; }
 

xs/src/libslic3r/Polyline.hpp

@@ -21,6 +21,14 @@ public:
     Polyline(Polyline &&other) : MultiPoint(std::move(other.points)) {}
     Polyline& operator=(const Polyline &other) { points = other.points; return *this; }
     Polyline& operator=(Polyline &&other) { points = std::move(other.points); return *this; }
+	static Polyline new_scale(std::vector<Pointf> points) {
+		Polyline pl;
+		Points int_points;
+		for (auto pt : points)
+			int_points.push_back(Point::new_scale(pt.x, pt.y));
+		pl.append(int_points);
+		return pl;
+    }
     
     void append(const Point &point) { this->points.push_back(point); }
     void append(const Points &src) { this->append(src.begin(), src.end()); }

xs/src/libslic3r/Utils.hpp

@@ -20,6 +20,11 @@ void set_resources_dir(const std::string &path);
 // Return a full path to the resources directory.
 const std::string& resources_dir();
 
+// Set a path with GUI localization files.
+void set_local_dir(const std::string &path);
+// Return a full path to the localization directory.
+const std::string& localization_dir();
+
 // Set a path with preset files.
 void set_data_dir(const std::string &path);
 // Return a full path to the GUI resource files.

xs/src/libslic3r/utils.cpp

@@ -103,6 +103,18 @@ const std::string& resources_dir()
     return g_resources_dir;
 }
 
+static std::string g_local_dir;
+
+void set_local_dir(const std::string &dir)
+{
+    g_local_dir = dir;
+}
+
+const std::string& localization_dir()
+{
+	return g_local_dir;
+}
+
 static std::string g_data_dir;
 
 void set_data_dir(const std::string &dir)