Fetch tax percentage from config

I would like to get the tax in a more dynamic way: from order/orderLineItem adjustments (or possibly shipment or invoice adjustments). I also see a scenario with different tax amounts, so instead of calculating it in UblBuilder::getBlob() we should probably take the inclusiveAmount and exclusiveAmount and taxAmount from the invoice.

That way you use whatever method was used to arrive at the tax stated on the invoice.

I have made a first patch that takes the percentage from the first orderItem Adjustment of the tax type. Far from perfect, but it's a start. I can add it to this issue if people are interested.

hi @finne, your patch is very welcome! I'll have a look at it as soon as I find some time.

Hi @bceyssens, I have added my changes to an issue fork branch.