CURR11 — removeExchangeRate() interface issue

Summary: The removeExchangeRate() interface may be too heavy handed. Modify
the semantics of this interface to support making an exchange rate
instance unsuitable for use (e.g. inactive). In this way, the exchange rate
instance would still be known to the component, but could no longer be used
in computations. It could however be extracted for reporting purposes, etc.
Would need interface accommodations though to indicate the extraction of
exchange rates that are “inactive”.

Not an issue