cellstr & strcat matlab inconsistency

[John W. Eaton]

On 23-May-2008, Jaroslav Hajek wrote:

| in current Octave strcat ("", "ab") produces an error instead of the
| obvious desired result.
| The problem can be fixed by having cellstr ('') producing {''} instead
| of {}, which is also consistent with Matlab.
| Attached is the change plus a test in strcat.m

I applied this change to the default and release-3-0-x branches.  It
didn't seem to cause any additional test failures on the release-3-0-x
branch, so it seems OK, but I'm not sure.  Do you know of any reason
to not apply it to the release-3-0-x branch?

Thanks,

jwe