Put new Gnus groups in the completion table
* lisp/gnus/gnus-start.el (gnus-group-change-level): Ensure that all new groups are in gnus-active-hashtb so that they can be completed to.
* lisp/gnus/gnus-start.el (gnus-group-change-level): Ensure that all new groups are in gnus-active-hashtb so that they can be completed to.