title: Better Enumerable.Range for both ascending and descending ranges?
body: <p>Suppose I have two points, <code>int x1, x2</code>, where <code>x1</code> can be larger, smaller or equal to <code>x2</code>. I want to generate all integer numbers between those two points inclusive (starting with <code>x1</code> and ending with <code>x2</code>), or just value of <code>x1</code> if both two points are equal. Is there any elegant way to generate <code>IEnumerable&lt;int&gt;</code> with those values? </p>