Merge changes made in Gnus trunk.

Merge changes made in Gnus trunk.

auth-source.el (auth-source-save-behavior): New variable to replace `auth-source-never-create'.
 (auth-source-netrc-create): Use it.
 (auth-source-never-save): Remove.
nnimap.el (nnimap-stream): Doc fix.
 (nnimap-open-connection-1): Reverse the order of the ports to that the prompted-for port is first.
gnus-start.el (gnus-get-unread-articles): Don't clobber the async retrieval by the no-group selection.
gnus-demon.el (gnus-demon-init): run-with-timer should be called with numerical parameters.
auth-source.el (auth-source-creation-prompts): New variable to manage creation-time prompts.
 (auth-source-search): Document it.
 (auth-source-format-prompt): Add utility function.
 (auth-source-netrc-create): Don't default the user name to user-login-name.  Use `auth-source-creation-prompts' and some default prompts for user, host, port, and password (the default generic prompt remains ugly).
 (auth-source-never-save): Add customizable option to never save info.
 (auth-source-netrc-create): Use it and improve save prompts.  Fix help mode excursion.