Adding Lua bindings for Vector2::Angle()

Source/Urho3D/LuaScript/pkgs/Math/Vector2.pkg

@@ -22,6 +22,7 @@ class Vector2
     float LengthSquared() const;
     float DotProduct(const Vector2& rhs) const;
     float AbsDotProduct(const Vector2& rhs) const;
+    float Angle(const Vector2& rhs) const;
     Vector2 Abs() const;
     Vector2 Lerp(const Vector2& rhs, float t) const;
     bool Equals(const Vector2& rhs) const;