matlab compability of str2func

[John W. Eaton]

On 12-Jun-2009, Norbert Froehlich wrote:

| I think there is no 'real' advantage exept the less effort, to make  
| matlab code work in octave. It's really only for compability.

Although I also think it is a bit useless, I checked in the following
changes (unfortunately two changesets since I pushed a bit prematurely
on the first one).

  http://hg.savannah.gnu.org/hgweb/octave/rev/2ca8879a140c
  http://hg.savannah.gnu.org/hgweb/octave/rev/70e0d3b1f26f

jwe