[vz-dev] [volkszaehler/vzlogger] ccb6d8: fix combined use of `interval` and aggregation

[Thorben T.]

  Branch: refs/heads/master
  Home:   https://github.com/volkszaehler/vzlogger
  Commit: ccb6d8ee49408cf6eb67b8d29492fcf7e82159d0
      https://github.com/volkszaehler/vzlogger/commit/ccb6d8ee49408cf6eb67b8d29492fcf7e82159d0
  Author: r00t <r00t at constancy.org>
  Date:   2021-11-05 (Fri, 05 Nov 2021)

  Changed paths:
    M src/threads.cpp

  Log Message:
  -----------
  fix combined use of `interval` and aggregation

it seems combined use of `interval` and aggregation was never considered.
the expected use-case of aggregation is to reduce the (externally determined)
rate at which a meter is generating data.
but some users want to use it create averages over data collected at a
configured `interval` - so let's support that.