simmer 3.4.1

New features:

• Prioritization (priority, preemptible, restart) has been moved from
  seize() to add_generator() (#69). This leads to a more natural
  interpretation of prioritization values as attributes of arrivals from the
  same generator, rather than attributes of a seize(). Still, prioritization
  values can be redefined dynamically from inside a trajectory with the new
  activity set_prioritization().
• New optional post.seize and reject sub-trajectories in seize() and
  seize_selected() (#49). This feature allows us to fine-tune what happens to
  an arrival if it cannot seize a resource: instead of getting dropped, it may
  execute a given sub-trajectory.
• New clone() and synchronize() activities (#71). clone() implements the
  workflow pattern in which an entity is processed in multiple parallel threads.
  The user can define a different sub-trajectory for each clone. With
  synchronize(), multiple parallel clones converge and are synchronized: only
  one continues (the first or the last to arrive), and the others are removed.
• New batch() and separate() activities (#45). They can be used to implement
  a rollercoaster process: batch() collects a number of arrivals before they
  can continue processing as a block, and separate() splits a previousl
  established batch.
• New renege_in() and renege_abort() activities (#58). They can be used to
  set or unset a timer after which the arrival will abandon.

Minor changes and fixes:

• If a branch()'s option returns 0, the arrival skips the branch()
  and continues to the next activity instead of throwing an index out of range
  error (#70).
• Throw errors on incorrect releases (#72).
• Remove deprecated convenience function every() (#65) and branch()'s
  deprecated argument merge (#57).
• New "The Bank Tutorial: Part I" vignette, by Duncan Garmonsway @nacnudus (#68).
• Update "Advanced Trajectory Usage" vignette.
• 3.4.0 (untagged) -> 3.4.1: Fix memtest notes and memory leaks on CRAN (heap-use-after-free).