parse aliased keywords. (see #21)

Expansion to s-expression will return a namespaced keyword without
resolving the alias. This is in accordance with the expectation that a
`:token` node returns a token, not a nested structure.

(An alternative approach would have been to generate the form
`(read-string "::ns/x")`.)

src/rewrite_clj/node/keyword.clj

@@ -35,10 +35,7 @@
 
 (defn keyword-node
   "Create node representing a keyword. If `namespaced?` is given as `true`
-   a keyword à la `::x` (i.e. namespaced to the current namespace) is
-   generated."
+   a keyword à la `::x` or `::ns/x` (i.e. namespaced/aliased) is generated."
   [k & [namespaced?]]
   {:pre [(keyword? k)]}
-  (assert (or (not namespaced?) (not (namespace k)))
-          (str "invalid namespaced keyword: :" (pr-str k)))
   (->KeywordNode k namespaced?))

test/rewrite_clj/parser_test.clj

@@ -50,6 +50,7 @@
   ":ns/key"                    :ns/key
   "::1.5.1"                    ::1.5.1
   "::key"                      ::key
+  "::xyz/key"                  :xyz/key
   "sym"                        'sym
   "sym#"                       'sym#
   "\"string\""                 "string")