Anchor regexes used in supply search

As requested in http://forum.dominionstrategy.com/index.php?topic=8163.msg377805#msg377805, this should avoid matching Black Market when searching for Market.

Instead of searching for the regex `Market`, we search for `(^|, )Market($|, )`, which will match only if the search term is bracketed on each side by either comma-space, or the start/end of the supply string.