Index fixings

Fix	Base class representing a fixing instrument.
ForecastFix	A class representing a forecast fixing.
ForecastFixGroup	A class representing a forecast fixing group.
FXFix	A class representing an FX fixing.
FXFixGroup	A class representing an FX fixing group.
FXForwardPoints	A class representing an interest rate fixing instrument.
FXVolatilityFix	A class representing an FX volatility fixing.
InterestRateFix	A class representing an interest rate fixing instrument.
InterestRateFixGroup	A class representing an interest rate fixing group.
IntradayFix	A class representing an intraday fixing.
MacroEconomicFix	A class representing a macroeconomic fixing.
MacroEconomicFixGroup	A class representing a macroeconomic fixing group.
SyntheticFXFix	A class implementing synthetic FX fixings.