Initial pull in time integration adapters

For all the integration adapters, it is unclear how to deal with the first pull when no time span is available.

Currently, AvgOverTime and SumOverTime with non-time-normalized data return the available single data entry, while SumOverTime with time-normalized data multiplies that entry with a user-defined duration (could e.g. be 0 or the target's time step).

Ideally, components should ignore the first pull, but they can't know that there is an adapter.