MultipleFinCalendar type added

UPDATE:

- Calendar type hierarchy update. Single & Multiple FinCalendar parent
types inserted after FinCalendar to allow better handling of multiple
calendars. The MultipleFinCalendar type should be the type used for
most other types that need a calendar field. The SingleFinCalendar type
should be used to define calendars in singular circumstances.
- isgoodday method updated to use new MultipleFinCalendar type.

NEW:

- MultipleFinCalendar constructors
Added cash indices; mod IBOR index class

NEW: Cash indices
UPDATED: compounding field of IBOR index class removed as all are
Simply compounded.