Port some of the theme setup functions from functions.php to the FSESU_Theme Class file and made some corrections

Changed the following action hooks to ensure the functions are initialised properly  so that it is initialised correctly
    theme_support function from init to after_theme_setup
    constants function from init to after_theme_setup
    styles function from init to wp_enqueue_scripts
Added menus function to FSESU_Theme class to register the menus, including a call to the after_theme_setup hook in the Construct function
Added widgets function to FSESU_Theme class to register the sidebars/widget areas, including a call to the widgets_init hook in the Construct function