20180104 BER (minor) Display licensing information with --version and
  usage. Implementation idea: change this when moving away from optparse.

20170709 BER: Give scripts/getan-eval.py a more specific name and add
  it as a script to be installed.

20170529 BER: Python compatibility: switch from deprecated optparse module
  to argparse. Affects getan/main.py and scripts/getan-eval.py.

20170504 BER: Some multi-user installations do not want a logfile by default.
  We could solve this requirement by making it configurable.

20170317 BER: Reproduce and then fix a defect: that it is surprising which
  entries are moved by `m` or deleted by 'd'.
  It probably has to do how multi-selections are handled. Maybe they
  are not cleared properly at the end of an operation.
  One description: It happens when you have changed a lot of entries
  from different projects (I assume), e.g. by editing the description,
  the length or timedate and then use move where you intend to only move
  one, the unwanted result is several moved entries.

20160912 BER: Better code: states.py: classes EditEntryState and
  AdjustEntryState have same methods exit() and set_focus(), maybe join them?

Older:

- Create a 'Help-Widget' to give the user an information about all possible
  keys.

- reimplement RPN input for current getan implementation (28489e672e61)

- The sum of previous times and currently running time should be displayed as
  in previous versions of getan.

- The currently running time should be shown near the project.