Products: switch for including and excluding taxes for product-prices and groups

In Germany it's kind of state of the art to differentiate between documents (invoices, quotes etc.) for private and business-customers. But Invoice Ninja just let us choose for all customers if a document-item's prices are including or excluding taxes. There's only an option to switch within the single invoice. I would like to make the feature-request to add the following settings: – self calculating tax-including netto- or gross-prices as it's possible within expenses but for all products; so one can chose to input the netto or the gross-price and the software automatically calculates the other one – group-settings for document-items having wheather included or excluded prices – an option to chose different prices per product and per group – another option to save a manually changed price of a product within an invoice as a "special price" for the actual customer (S A G 'E has such an option, and it's very handy!) So for customers w…