9.2.1

Changes from previous version:

Fixes

• Force the use of 'fork' as the start method (629064c, #116)
  This makes byexample to work on MacOS with Python 3.8 again.

Others

• minor fixes in the documentation.
  (see df6325c, b57c7cc, 445c4eb, 72098fd)
• continuous integration smoke tests for macOS (7b0dff9)