Major Refactoring (will need some cleanup)

This refactors the plugin from one mega syntax file into multiple
classes.

The plugin now focuses on one usecase: listing files that are external
to the wiki and making them downloadable. All other usecases have been
dropped. Also a bunch of other options have been dropped.

A new dispatcher makes it possible to deliver files without the need to
have the webserver pointing at them.

conf/default.php

@@ -4,6 +4,8 @@
  * Options for the filelist plugin
  */
 
+$conf['paths'] = '';
+
 $conf['allow_in_comments'] = 0;
 $conf['allowed_absolute_paths'] = DOKU_INC;
 $conf['web_paths'] = DOKU_URL;