tag matching and ApplicativeContex

To date, the Ark is really great for information which is reasonably well structured, with tags and the sCmd the only means of identifying content which was not so well structured.

Meanwhile, Norm has been using tags extensively to classify much of the content he is adding to his own Ark, and has suggested a significant enhancement that would give the Ark a tremendous capability for working with unstructured (but tagged) content. (Yes, I'm excited!)

The idea is to add tag matching to the ApplicativeContext. VisibleTopics then would include all the appropriatly tagged Topics. This gets around the need to structure everything. For many things, simply adding the appropriate tags will be good enough.