GCstar forums - Creation of Gitlab group GCstar

In order to apply for the Gitlab's open source program, I migrated GCstar, GCstar_Scan_NG and GCstar_Viewer from the Kerenoc namespace associated to my account to the GCstar namespace associated to a group.

In all URL related to the Gitlab repositories, please replace https://gitlab.com/Kerenoc/ by https://gitlab.com/GCstar/

People who have forked the repository may need to take some actions to remain synced with upstream commits.