Flow bugfix releases: 3.3.20, 4.0.14, 4.1.8, 4.2.4

A number of bugfix releases have been done for Flow, containing a couple of bugfixes and documentation improvements. Especially users of 4.2 are highly recommended to upgrade, due to some regressions that were introduced with the change to PHP 7 typehints in Flow 4.2.

Flow - 4.2.4 Changelog
Flow - 4.1.8 Changelog
Flow - 4.0.14 Changelog
Flow - 3.3.20 Changelog