As mentioned by netvor on IRC, the unbalanced transaction error was
not too clear when postings all have the same sign.
Some other wording has been clarified, and the main error message is
now shown on multiple lines for readability (at the cost of
predictability/grepability..)
There's also a probably unnoticeable change: selecting which parts of
the error to show is now based on display precisions (reusing the
balanced check logic), rather than original precisions.
924ec1c98d