This ensures that the text and the close icon don't overlap, regardless
of the length of the title. The title div grows to use all available
space, while ensuring the text breaks if necessary to prevent it from
pushing the close icon offscreen.
Alternative to #580
This reworks changeset descriptions to use italics instead of header
elements, in order to make them more like quotes.
Care has been taken to make sure that there is still a header element
as the first element of the common details partial, in order to make
the history pages look right (where the partial appears multiple times).
