Add CompHEP to conda-forge

[matthewfeickert]

Needed to work with LanHEP (c.f. Issue #84).

https://theory2.sinp.msu.ru/doku.php/comphep/download/main

CompHEP's website seems like it could go away with no warning, so a https://github.com/hep-packaging-coordination/ mirror should be created.

[matthewfeickert]

Requirements as given by https://theory2.sinp.msu.ru/doku.php/comphep/download/main:

• Linux RedHat-6.X or later, Scientific Linux CERN 3 or later. It should work under any UN*X OS, but not guaranteed.
• gcc (version 3.0 or later), g77 (version 3.0 or later) or gfortran (version 4.0 or later)
• 128MB RAM. This is strongly dependent on the task.
• 30MB HDD for installation.
• ISAJET (as a CERNLIB library) and CERN Mathlib library, if you are going to use MSSM models.

So looks like will need to build ISAJET and CERN Mathlib first for full support for CompHEP v4.5.2.

https://theory2.sinp.msu.ru/lib/exe/fetch.php/comphep/download/comphep-4.5.2.tgz

• c.f. Add ISAJET to conda-forge #88