reorganize products/inventary

• product menu should be called almacen, with entries (productos, entradas almacén, alta de proveedores, alta de codigos)
• product list should have title productos en almacen
• list header nombre should become producto (inventary list and product list)
• inventary list should have title entradas almacen
• create supplier title Alta de proveedores
• put the inventary list into the same page of the inventary creation and title it Listado Entrada