Download & set-up HITEMP files on server

[erwanp]

Related to #85 , I think Radis-App can handle HITEMP.
This would be a first, as currently Spectraplot has this functionality but the algorithm there is not able to cope with many lines, hence it is very limited.

If @suzil you confirm to me that the server is never restarted, then it's easy and it's a one shot action :

• I already prepared files download_hitemp.py, download_hitemp_CO2.py, download_hitemp_H2O.py which would only have to be uploaded and executed on the server
• all the rest is automatic
• (CO2 and H2O may take ~2-3 hrs total)

Then we would only need to have a frontend/backend change similar to the #570 #562 improvement.

[suzil]

If @suzil you confirm to me that the server is never restarted, then it's easy and it's a one shot action :

You are correct: server has a persistent file store that never gets reset.

[suzil]

Whomever takes this ticket, please create a PR to add the required scripts and after they're merged, I'll run them on the server.

[erwanp]

Done !