[octave forge] (matgeom-dev) external repository in sync

[Juan Pablo Carbajal]

Dear all,

I have synched the external repository matgeom [1] with upstream.
I had to duplicate the remote branch gnu-octave and use master to add
an extra documentation  file GITSETUP.md.

I would appreciate if anybody reviews the release workflow described
in GITSETUP.md and provide suggestions.

I am using a Makefile derived from the template, feel free to provide
suggestions there as well.

I will wait a few days and then upload a release of the matgeom
package. when the release is accepted, I will proceed to release the
new version of the geometry package.

Thanks for all the support and sorry for the delay.

Regards,

[1]: https://sourceforge.net/p/octave/matgeom/