Setting an event complete at the same time as adding a task is unstable.

[davetcc]

When a task is added in the exec() method of an event, and that event is marked completed in the same method, there is currently instability. The newly added task is often times not run and the attempted removal of an already released task causes instability.

[davetcc]

This is for emergency patch release, as soon as tested on a range of boards.

[davetcc]

Unit tests passed on AVR, SAMD, ESP8266 and ESP32. Testing applications on all platforms.