Website - provide possibility to authorize via Google, FB, VK etc.

Currently www.opencascade.com requires users to create accounts in order to be able to download files and/or post messages on the forum. This is regarded as inconvenient and annoying by many people.

Modern technologies allow avoiding the need to create new account, by using existing account on social network or other public site providing open authentication services, like Google or VK.

It is proposed to implement this possibility for OCCT web sites.
I suppose that the number of permissions requested from the service should be minimal (basically user name and e-mail should be sufficient).

It would be very useful to have possible to associate existing account with externally authenticated account. In line with this, it would be great to make it possible to associate account on dev.opencascade.com with that on www.opencascade.com -- it would be a step towards smooth integration of our split-brain sites.


Links:
https://oauth.net/
https://www.drupal.org/project/oauthconnector
https://www.drupal.org/project/gauth
https://www.drupal.org/project/fboauth
https://www.drupal.org/project/linkedin
https://www.drupal.org/project/vk_openapi