Refactoring, documenting, securing from XSS/SQL-Inj

Solid refactoring, formatting and documenting the existing code.
Created a new lib php file - db-functions.php and moved 2 commonly used
methods there.
Secured the models from XSS or SQL-injection attacks, escaping  all user
inputs.
Removed completely the forum functionality and all related files.
Visual and layout changes on the login/register pages, removed the guest
prompt and placed the sign in button in the nav bar.
Added handling if the user tries to access product landing page with a
non-existing or inavlid ID.