(bug 36788) Add classes to containing row on watchlist/history

(bug 36788) Add classes to containing row on watchlist/history

Each line on the watchlist and on the history pages should have a
specific class to indicate the "updated since my last visit" status,
to allow for more comprehensive styling than is possible with individual
elements embedded within the line.

Also some cleanup: turn the $classes variable in the enhanced watchlist
code path into an array, and change the bolding of titles in the
watchlist from <strong> tags to styling via CSS.

Change-Id: I90bc95db061274d4de782578a4e91f954481adfd