Conversion Utilities; new function to update the Interest Rate

Conversion Utilities includes a new function AccountInterestRateUpdate. This allows a Fixed Term Loan's Ongoing Interest Rate to be amended.

This function does the following:

1. Adds an Audit record showing the original and new Interest Rate.
2. Adds an Account History record of type "Interest Rate Change" with a Reference of "Conversion".
3. Updates the original Account Calculation record's Ongoing Interest Rate - overwriting the original Interest Rate.

Note, this is a hack and you should be aware that the original Interest Rate is overwritten on the Account Calculation. However, the orginal Schedule will still be correct. A warning message has been added to the Account form, Financial page if displaying the Opening calculation.