* gnus-nocem.el (gnus-nocem-scan-groups): Add autoload cookie; scan latest

* gnus-nocem.el (gnus-nocem-scan-groups): Add autoload cookie; scan latest
 NoCeM messages instead of old ones.
(gnus-nocem-check-article): Fix regexps so as to match to PGP delimiters that
 are recently used.
(gnus-nocem-load-cache): Add autoload cookie.

* gnus.el (gnus-use-nocem): Enable it to be set to also a number.

* gnus-start.el (gnus-setup-news): Scan NoCeM messages if a group level which
 is larger than gnus-use-nocem is specified.

* gnus-group.el (gnus-group-get-new-news): Ditto.