New Customer statement module for 1.2.18

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We are working on a customer statement module for 1.2.18 that will show
each invoice total as one line  with date and each payment with check # as
a line (weather received on an invoice, as cash > receipts, or AR > add
transaction) with date. We will cluster by invoice #. As is the custom
here.

Right now the statement does not show amounts due and payments separately.
 It subtracts payments received at time of invoice from the invoice amount
so the total for the invoice does not match the original invoice. The
custom here and what our customers expect is to see a invoice number, the
invoice amount, the date, then a check number or payment ref#. Next line
would be amount they paid and the date it was received. and so on. With a
balance due at the bottom.

The one thing to make it compatible with other installs would be to figure
out how the AR checking account(s) are determined since we have hard coded
that for now.

Cheers Turtle