Merged with Master
Merge branch 'master' into darren
 commit Niall
Logout button on main tab panel
Stock now subclass of product, and product ID removed.
IDs now associated with Sales and Orders, not Invoices.
Sale and Order changed accordingly to changes with product and stock
classes.
Merge branch 'master' into darren
Merge branch 'master' of https://github.com/fcpteam1/project
ShopNoGUI update and Supplier Number and Address added