Merge the autobackup plugin into the braincase plugin

[hamstar]

Need to build the autobackup plugin into the braincase (var/lib/dokuwiki/lib/plugins/braincase) plugin.

This could be done by setting up the braincase plugin folder structure like so:

|- braincase
 \ - action
   \ - dropbox.php
    |- memories.php
    |- mailstopper.php

The class names become action_plugin_braincase_dropbox etc.

As it stands the autobackup plugin contains code specific to braincase. This way allows a merger while still separating concerns.

See plugin file structure for help.