Account Calculation Payments; added additional Business Layer functions to assist scripting

Additional Business Layer functions have been added to finAccountCalcPayments to assist scripting calculations.

These functions help manipulate the list of overriding Payments, and include the following:

CreateBlankRegularPayments; populates the list with blank Regular Payments.
RemoveBlankRegularPayments; removes any blank Regular Payments from the list.
RemoveIgnored; removes any "ignored" payments, eg Regular payments not dated on a regular payment date.