* gnus-offline.el: Rewrite to work with pGnus v0.74 based T-gnus.

* gnus-offline.el: Rewrite to work with pGnus v0.74 based T-gnus.
* gnus-ofsetup.el: Ditto.
* pop3-fma.el: Removed because after pGnus0.73 , pGnus can treat multiple pop3
account.
* read-password.el: New file.
* gnus.el (running-pterodactyl-gnus-0_73-or-later): Provide as a new feature.
* mail-source.el (mail-source-read-passwd): Don't load "passwd" if the
function `read-passwd' already exists.
* gnus-start.el (gnus-read-active-file): Eliminate duplicated select methods.
* gnus-group.el (gnus-group-catchup-current): Fix typo.
* gnus.el (gnus-version-number): Update to 6.10.056.
* Sync up with Pterodactyl Gnus v0.74.