Account Calculations; user friendly conversions of Term made when Payment frequency changed

In the Account Quotation and New Account wizard user friendly conversions of the Term are made when the Payment frequency is changed.

Note, this only applies if "Term" entry method is used, and occurs when the "Payment" cycle changes.

Term and First Payment period are updated to match the payment frequency if possible, ie the following conversions are made:

1y = 12m = 26f = 52w (and any multiples thereof, this is actually first multiple of 6m, but includes years)
9m = 39w
6m = 13f = 26w (and any multiples thereof)
3m = 13w
2m = 4f = 8w
1m = 2f = 4w