D'oh - re-instate support for regex matches.

We do need to support a ref being given to _build_wrapper even in single mode,
because the user can provide a regex ref to match, e.g.:

    get '/beer' => require_role qr/^(Beer|Vodka)Drinker$/ => sub { ... };

So, add _smart_match(), to act as a much more wordy and less optimised
replacement for the much maligned and misunderstood smartmatch operator.

(I thought the smartmatch operator was refined, sublime, and makes you feel
fine, but apparently using it is Naughty, naughty, very naughty.)