New Function rectint.m

[John W. Eaton]

On  2-Mar-2008, Bill Denney wrote:

| I was feeling like doing something so I wrote the rectint.m function.  
| Changelog is in the changeset.

I applied this patch with a few style changes.  I also added a check
to ensure that the arguments are 2-d arrays.  Is that OK?  As it is,
your function silently ignores the additional dimensions.  Is that
desirable behavior?

Finally, I'll take this function since it seems to work, but perhaps
there is a way to vectorize it and avoid the nested for loop and
subfunction?

Thanks,

jwe