Marked getItem() as deprecated, renamed it to getItemByIndex(), and added a new getItem() that uses GtkTreeIter instead of an index. This is for one last change in itemeditor.c to get rid of another itemsModel() call; presently order.c is broken so I'll fix that after fixing itemeditor.c.
Removed itemsModel() calls from itemeditor.c, replacing with dedicated getItem() calls.
Quick patch to fix the Order window to have it work again; a proper fix will be introduce during the cleanup that will happen next.
Got rid of getItemByIndex() by changing Order to not use indices at all.
Renamed subtotal() to total() and changed instnaces where subtotals were used when totals were wanted instead.
Added a shell script to check the number of files that use each function in simplesale.h.
Marked some functions in order.c static and deleted the redundant orderModel().
Removed listStoreIterIndex() and listStorePathIndex() as nothing uses them anymore.
Removed shiftNewOrder(); that's only used internally, and its contents can be moved right into the internal signal handler for the New Order button.
Fixed compiler errors in the previous commit.