hiccup-style adapter doesn't cope well with transformation results

[cemerick]

This was surprising:

> (html (at (html [:a])
          [:a] (content "foo")))
ClassCastException   [trace missing]

(Finding the cause was "fun"; there's no stacktrace because the failure is in the destructuring of the first map element in the vector result of at.)

Anyway, the workaround is easy (seq around the result of at). The impl of nodify should probably fall through to the (sequential? node-spec) case if node-spec is a vector with a map for a first element.

[fdserr]

Trace back when compiled against clojure 1.7: ClassCastException clojure.lang.PersistentArrayMap cannot be cast to clojure.lang.Named clojure.core/name (core.clj:1524) Incoming...

[fdserr]

Would this fit?

(html (at (html [:a])
             [:a] (content "foo")))

=> ({:tag :a, :attrs {}, :content ("foo")})