[octave forge] new external package: matGeom

[Juan Pablo Carbajal]

Dear OF leaders,

I would like to submit my fork of matGeom[1] as a condidate for an
External Package at OF.
Geometry (a community package) extends the functionality of matGeom
and provides several matlab compatible geometric functions.
Without matGeom as a package discoverably by `pkg -forge`, the update
of geometry becomes problematic for the user.

This would also simplify the structure and reduce the size of the
current geometry package[2,3] (an overall increase in
maintainability).

Thank you for your consideration.

[1]: https://github.com/kakila/matGeom
[2]: current development branch
https://sourceforge.net/p/octave/geometry/ci/default/tree/ bookmark
`release` (SF web doesn't support bookmakrs)
[3]: simplified package
https://sourceforge.net/p/octave/geometry/ci/default/tree/ bookmark
`matgeom_separation` (SF web doesn't support bookmakrs)