major code changes to make it more streamlined

Added some error checking abilities.
Added default value for parameter in mail_api_authenticate().
Bug and implementation fixes, etc.

Changed name of function mail_api_server_info() to mail_api_server_configuration() to avoid conflict with the Services module's hook_server_info.
Changed $folder parameter default from 'all' to array('ALL_FOLDERS') in mail_api_pager_search().

Added mail server authentication related functions, and improved on other functions to make them work better with the authentication functions.

Added new main settings page for Mail API, and adjusted menu paths accordingly.  This helped the url's make more sense and stopped the breadcrumbs from being broken when adding/editing/deleting mail server configurations.  More will be added to the main settings page.

Inserted $form_state parameter before $server_id parameter in mail_api_form_edit_server() and mail_api_form_delete_server() functions.  This solved the problem with not being able to edit and delete configure servers.

Total re-write.  The code is much cleaner.  The API is cleaner.  Way fewer functions.  The hooks are much cleaner and make a ton more sense, using module_invoke to execute them instead of my own crazy code in the previous version.  The only function in this module I haven't gotten to is mail_api_filter, for providing automatic email filtering/sorting capabilities for moving messages to different folders based on different criteria.  Other than that, everything's mostly implemented, and hopefully functioning properly...lots of testing needs to be done, but I need to get the IMAP API module up to par with this one now, so it can be tested.