Error with pkg.m (== isspace does work with cell arrays anymore)

[Michael Goffioul]

I have an error with recent mercurial code, in pkg.m. It reduces to
the fact that isspace does not work anymore on cell array of
strings. The error occurs around line 1299:

  if (! all (isspace (filenames)))

where filenames is a cell array of strings. I'm not sure what's
the correct way to fix this.

Michael.