Refactor files, classes, and i18n

Refactor the filenames and classnames to match the layout and naming
conventions of the default extensions.

Remove the custom i18n file loading code and start using the $messages and
$specialPageAliases arrays.

Bump the version to 0.2 since this commit requires changes to
LocalSettings.php.
Update the Akismet PHP5 class to 0.5
Convert to Markdown documentation