Commit ab9ca2df (bigarray: Add support for FORTRAN ordering) added
ability to define array order, but there I made a mistake of not caring
about how previously-saved to DB arrays would be read back.

The thing is BigArray gained new data member ._order which is
automatically saved to DB thanks to ZBigArray inheriting from
Persistent; on load-from-db path we just read object state from DB,
which for ZBigArray is dict, and restore object attributes from it.

But for previously-saved data, obviously, there is no 'order' entry and thus
this way restored objects are restored not in full to current code expectations
and it can boom e.g. this way:

    zarray.resize((new_one,old_shape[1]))
  Module wendelin.bigarray, line 190, in resize
    self._init0(new_shape, self.dtype, order=self._order)
  AttributeError: 'ZBigArray' object has no attribute '_order'

Solution to fix is: on restore-from-DB path, see if a data member is not
present on restored object, and if it has default value in BigArray set it to
that.

( code to get function defaults is from
  http://stackoverflow.com/questions/12627118/get-a-function-arguments-default-value )

/cc @Tyagov, @klaus