(top): Update comments.

(top): Update comments.
(gnus-namazu-indexed-servers): Abolished.
(gnus-namazu-index-directories, gnus-namazu-command): Changed the
default value.
(gnus-namazu/group-name-regexp): New internal constant.
(gnus-namazu/indexed-servers): New function.
(gnus-namazu/setup): Not initialize `gnus-namazu-indexed-servers'.
Add the entry for ephemeral groups generated by
`gnus-namazu-search' to `gnus-group-name-charset-group-alist'.
(gnus-namazu/group-prefixed-name): Fix.
(gnus-namazu/search): Stricten checking the return value of
`gnus-namazu/call-namazu'.  Install changes in order to avoid the
difference between regexp-opt module of FSF Emacs and one of XEmacs.
(gnus-namazu/get-target-groups, gnus-namazu/get-current-query):
Refer `gnus-namazu/group-name-regexp'.
(gnus-namazu-search): Slightly modified.