Experimental post_initialization hook for ruby-processing

Sketch run from jEdit, two sketchs for price of one

Previously I experimented with classic initialization hook (that avoids need to call super) here is an experimental version of ruby-processing with a post initialization hook. Seems to work!!! here are the bits that enabled it in app.rb

def initialize(options={})
  super()
  post_initialize(options)
  $app = self
  proxy_java_fields
  #############
  # omitted code
  ############
end


def post_initialize(options)
  nil
end