Making specfun pkg unmaintained

[Colin Macdonald]

Hi Carnë et al,

I've prepared a release for Symbolic.  This release has some functions
from the specfun pkg [1] but I have not finished moving them all
over---mainly because the remaining functions are of poor quality.

Carnë said:

> We should make a new release of the specfun package before the next
> release of the symbolic package (or maybe just mark it as
> unmaintained).

I suppose unmaintained feels right to me.

Here is a summary:

  * Symbolic 2.4.0 will shadow/conflict with the current specfun-1.1.0:
    dirac, heaviside, laguerreL, and lambertw: numerical functions
    we've already moved over and dropped from specfun tip.

  * With Octave 4.0.1, specfun-1.1.0 shadows:
    ellipj, ellipke, erfcinv, expint.

  * With Octave tip, as above but also:
    psi.

  * The Specfun->Symbolic transition discussion is at [1].

cheers,
Colin

[1] https://savannah.gnu.org/patch/?8644