finAccount Business Layer object; added denormalised Balance values

The Account database table has a number of denormalised values.

These values are normally retrieved from the finAccount object via GetBalance functions - which return the value as a parameter and a Boolean return value indicating success. These functions also apply various logic and take into account a "Date As At" parameter.

To add more convenience the finAccount object now also includes the following Read-Only Properties:

Balance
BalanceOverdue
BalanceOverdueContractual.

These properties return the Balance, Overdue Balance and Contractual Balance of all Transactions for the Account - including future dated Transactions.

In addition, these values may NOT be the same as returned from GetBalance, GetBalanceOverdue and GetBalanceOverdueContractual if post Maturity as they do not adjust for Credit Balances etc.