CART needs currency support

• Feature request

Among several, there is one very big limitation of the shopping cart:

It cannot handle currencies! I wonder why no one saw this before (and I have to add, when debugging the translation of Tiki, it did not occur to me either). Cart must store the currency linked to all products. The currency of the user must be user-selectable (Of course, at the admin's discretion, the set of available currencies must be limited). We need to modify the data structure. The currency MUST become a separate field, and with that the price becomes strictly numeric (It could and should be discussed if we make that integer in the small currency units, but display it with the decimal comman/point inserted) and the currency should be strictly the three-letter ISO code, but a representation of that could be selectable (€ for EUR for instance).

If user currency and currency of any stock item differ, currencies must be converted. Currency conversion isn't easy. The first and easiest solution is having fixed conversion rates. These MUST be prominently and transparently displayed to the user, as they become part of the contract between the user and the admin/owner of the Tiki. Also, some sort of fee for currency conversion must be selectable by the admin (0 of course being the default), and it, too, must be prominently and transparently displayed.

When fixed rates have been established, the next level of comfort might be automatically set/updated rates. For that, we would have to find a reliable provider. Also, since all providers might for some reasons fail to supply data at any given time in the future, a default minimum and maximum rate must be selectable by the admin.

At first, I thought this could have been overlooked because of a domination by the US, but then it crossed my mind that even Americans have the need for currency conversion, because they got US and Canadian dollars, and when they sell internationally, also Australian and New Zealand dollars...

In Europe it is much more complex. Most countries have the Euro, but not all. Great Britain does not, but now it's not even part of the EU anymore. In the German speaking countries we have Euros (Germany, Austria) and Swiss Francs. Even though Switzerland is also no member of the EU, the fact that a large portion of Switzerland speaks German leads to Swiss users using German Tikis, and vice versa.

This bug has been demonstrated on show2.tiki.org

Please demonstrate your bug on show2.tiki.org