Do not pass the $key to sqimap_login, that takes care of that itself.

Do not pass the $key to sqimap_login, that takes care of that itself.
Also remove any globals that are not needed anymore because of this change,
or because they're already set in init.php.

I believe that we should move to a sqimap_login() without any parameters,
but this is a good first step.

git-svn-id: https://svn.code.sf.net/p/squirrelmail/code/trunk/squirrelmail@11476 7612ce4b-ef26-0410-bec9-ea0150e637f0