Changes for clojure.core/print-method

pangloss on Fri, 31 May 2013
(deftype XYZ [])

; without custom print-method defined:
user=> (prn (XYZ.))
#<XYZ user.XYZ@2670d85b> 

(defmethod print-method XYZ [v ^java.io.Writer w]
  (.write w "<<-XYZ->>"))

; with print-method
user=> (prn (XYZ.))
<<-XYZ->>