simmer 4.4.3

New features

• Add support for functions in when_activated() (#250).
• Add support for dynamic batch sizes (#258 addressing #245).

Minor changes and fixes

• Fix multiple reporting of ongoing arrivals (#240).
• Set package namespace as parent of simmer and wrap environments (#241).
• Fix arrival restart after queue drops (#257).
• Fix segfault printing activities with empty vectors (#253).
• Fix source behaviour with missing values, which now stop arrival generation
  in the same way as negative values do (#256).
• Fix deactivate(), which now unschedules future arrivals (#249).