Rename util_show_error_page() to util_show_error_page_and_exit() and redirect() to util_redirect_and_exit()

so it is explicit that we exit in those functions that so we know it isn't necessary to put an exit after
we call them

appbrowse.php

@@ -35,7 +35,7 @@ if( empty( $aClean['iCatId'] ) )
 }
 
 if(!is_numeric($aClean['iCatId']))
-	util_show_error_page("Something went wrong with the category ID");
+	util_show_error_page_and_exit("Something went wrong with the category ID");
 
 // list sub categories
 $cat = new Category($aClean['iCatId']);