WIP: Smyth grammar reader

Continuation of #189 

Enables a user to click on a Smyth category and pull in the grammatical definition right into the plugin.

A quick and dirty solution - might solve this differently in the future (especialy for potential reuse).

The whole thing is not very efficient. We are retrieving html documents from a server, cache them in case we need them again and run a jQuery selector to pull out specific parts of these files, which we represent to the user.
 Such a directive will also enable us to go through the grammar more freely - eventually a position we want to be in, so that we can really use visualizations of the grammar in other places as well. Also needs much better indices for that. More tasks for the future...

Styling of the HTML output might also be an area for improvement. Sometimes we're stuck with a not so brilliantly formatted TEI-to-HTML transformation in the first place, in other cases we can do better.

Adds a nice utility classes for handling Ranges - it comes with a full spec suite, so check that for documentation.