Gave editinvoice.php a makeover, getting rid of the stupid two column design.
Fixed a bug that prevented the collection of unit price when "editing" a part.
Updating invoice.inc to Invoice.inc, to bring it into line with the style of the other Class Files.
Implemented marking invoices as "paid"
Parts now have an accessor function for their total cost, unitCost * qty. This cannot calculate tax, as the taxrate is not stored in PnL, so the taxrate must be calculated elsewhere.
Updated the Master page to the new system, and added a list of unpaid invoices to the master page.
First iteration of the Report system. Built Alpha stage taxreport page. It's not much, but it'll get me through this bunch of taxes.
General cleanup of taxreport.php