Rewrite functions.php to take account of new FSESU_Theme class

Removed the following functions from functions.php

 * fsesu_setup()
 * fsesu_custom_excerpt()
 * fsesu_excerpt_more()
 * fsesu_favicon()
 * fsesu_unautop_4_img()

Removed the "clean up <head>" actions from functions.php
Removed all references to widget.php as it is now incorporated into the FSESU_Theme class
Added a global definition for $fsesu and created a new FSESU_Theme object for it
Added code to define the site specific categories

Removed the fsesu_new_category() function from util.php

Closes #9