- initial unicode support

- initial unicode support
 . entry names will be converted to ascii. zip works with cp437
   when 7zip support will be added, unicode string will be supported
 . path and filenames are now encoded using php_stream_path_param_encode
   if the filename/path is used as entry name, it is converted to ascii
 . the stream (getStream and zip://) needs some tweak. I'm not sure if it
   should return unicode or binary, neither how to change the default. For
   now it returns unicode (seems to be the default :)
comments/suggestions welcome