This subroutine extracts a GTI sequence from a single DSS filter.
The pointer gti() should be deallocated after use.
subroutine getGtiFromFilter(set, filter, gti)
type(DataSetT), intent(in) :: set
type(DSfilterT), intent(in) :: filter
type(IntervalT), pointer :: gti(:)
end subroutine getGtiFromFilter