* Restore behavior of thresholded comments being greyed out (lost in 6fa0ae2cf).
* Set the `below-threshold` class for thresholded comments in the html instead of in javascript.
* Remove `include_below_threshold` param; it was always true when clicking "Show all comments".
Mark the edit form, new comment form, and unvote links as hidden in
html, instead of showing them by default then hiding them later in
Javascript. This eliminates flickering on page load.