BNZ GIFTS Direct Credit and Direct Debit; update list of valid characters

The list of valid characters for the "BNZ GIFTS (Direct Credit)" and "BNZ GIFTS (Direct Debit)" Bank Export formats have been updated.

Previously the valid characters accepted were:

-ABCDEFGHIJKLMNOPQRSTUVWXYZ 0123456789

this has been updated to:

0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxz -'&/#?:_.

Note, in addition the Kiwibank GIFTS file would omit lower case "y" characters.