In hindsight, it was a bad idea to allow manipulating the cart (entries)
in hook_checkout, because that hook is used by the `log` plugin. You now
get unused entries in the log.
Although that plugin should maybe have used hook_checkout_done, existing
log file readers (including scripts) and custom plugins may depend on
the CHECKOUT items in the log being before the BALANCE items.
Now implemented via a hidden user called '-cash'.
This also introduces the concept of hidden accounts, that begin with '+' or
'-', for result accounts and balance accounts. Future versions can further
use this for more detailed bookkeeping. The idea behind the sign is that
'-' accounts should be inverted to get the intuitive value. So if the account
'-cash' has -13.37, that means there should be +13.37 in the cash box (or,
well, once the rest of this is implemented and the initial values are then set
correctly.)
The signatures feature has been "experimental" since Perl 5.20 (May 2014), but
expected to stay. After 8 years I'm ready to take the risk :)
Have added Perl v5.28 (June 2018) as the minimum requirement, even though the
current revbank should work with 5.20, to see if this bothers any users. Perl
v5.28 is in Debian "buster", which is now oldstable.
The 'stock' plugin uses the 'product_id' field in the cart item, but
this was not copied by the 'repeat' plugin. The confusion is caused by a
mismatch between the API for RevBank::Cart->add and the internal
representation.
