Added Lua bindings for new IntRect utility functions.

Source/Urho3D/LuaScript/pkgs/Math/Rect.pkg

@@ -45,6 +45,7 @@ class IntRect
 {
     IntRect();
     IntRect(int left, int top, int right, int bottom);
+    IntRect(const IntVector2& min, const IntVector2& max);
     ~IntRect();
 
     bool operator ==(const IntRect& rhs) const;
@@ -54,6 +55,9 @@ class IntRect
     int Height() const;
     Intersection IsInside(const IntVector2& point) const;
 
+    void Clip(const IntRect& rect);
+    void Merge(const IntRect& rect);
+
     int left_ @ left;
     int top_ @ top;
     int right_ @ right;