AV1510: Add conditions on when (not) to use "using static"

[bkoelman]

Current rule:

Limit usage of fully qualified type names to prevent name clashing. For example, don't do this:

var list = new System.Collections.Generic.List();

Instead, do this:

using System.Collections.Generic;

var list = new List();

If you do need to prevent name clashing, use a using directive to assign an alias:

using Label = System.Web.UI.WebControls.Label;

[bkoelman]

@dennisdoomen Any thoughts on this?

[bkoelman]

Can this be closed? We don't seem to have any guidance here.

[bkoelman]

Looks like this was already addressed by #126, which got merged. Closing.