sph2cart added functionality

[Rik]

5/24/10

I was doing some GPS calculations and I had occasion to switch between
spherical and Cartesian coordinates.  The interface for sph2cart is:

[X, Y, Z] = sph2cart (THETA, PHI, R)

However, I find it more convenient to think of triplets in one vector space
being converted to triplets in another space.  For this it would be easier
if I could call sph2cart with matrix arguments and receive matrix return
arguments.

Is there any problem with adding the ability to call sph2cart on matrices
with column 1 = THETA, column 2 = PHI, column 3 = R?  This would add
additional functionality beyond the MATLAB function of the same name, but
wouldn't take away the ability to replace the Octave function one-for-one
in MATLAB code.

--Rik