finaly factored out PickleableObject

uses my nonclobbering file opener: safeOFW

class PickleableObject(object):
   """Generic pickleable class
   """
   def save(self,filename,clobber=False):
       """given an object, e.g. a taxon dictionary,
       pickle it into the specified filename

       Set clobber = True to allow overwriting of the
       output file"""
       import cPickle
       f = safeOFW(filename,clobber=clobber,append=False)
       cPickle.dump(self,f)
       f.close()

   @classmethod
   def restore(cls,filename):
       """given a filename, return an object containing the
       pickled data in that file"""
       import cPickle
       f = open(filename,'rb')
       obj = cPickle.load(f)
       return obj

I've been meaning to move this from a class that Peter wrote it in to originally at my request. It's quite nice to have it globally available.