new sunlight and skybox colouring collected from real world measurements (reports TBA)

Former-commit-id: 6abaa1e16d0fd7a71f95bd0265809aad9e34a425
Former-commit-id: bb871bd87072f27b9cc29594f9eed615351df5f8

src/net/torvald/point/Point2d.kt

@@ -49,6 +49,8 @@ class Point2d(var x: Double, var y: Double) : Cloneable {
 
     fun toVector() = Vector2(x, y)
 
+    fun copy() = Point2d(x, y)
+
     fun length(other: Point2d) = distSqr(other).sqrt()
     fun distSqr(other: Point2d) = ((this.x - other.x).sqr() + (this.y - other.y).sqr())
 }