Make the output of the change-svn-wc-format.py script a bit more user friendly.
Make the output of the change-svn-wc-format.py script a bit more user friendly.

* tools/client-side/change-svn-wc-format.py
  (LossyConversionException): add field lossy_fields.
  (Entry.assert_valid_format): tell user to use --force to procede with lossy
   behavior.
  (WCFormatConverter.write_dir_format): tell the user which field(s) are being
   dropped.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion