Transaction prices were being collapsed/misreported after close/open;
this is fixed. Now each separately-priced amount gets its own posting,
and only the last of these (for each commodity) gets a balance
assertion. Also the equity posting's amount is now always shown
explicitly, which in multicommodity situations means that multiple
equity postings are shown. The upshot is that a balance -B report
will be unchanged after closing & opening transactions.
