Andrew Heather authored Jan 13, 2022 and Mark OLESEN committed Feb 25, 2022

The runTimeControl function object can activate further function objects using
triggers. Previously the trigger index could only advance; this change set
allows users to set smaller values to enable function object recycling, e.g.

Repeat for N cycles:
1. average the pressure at a point in space
2. when the average stabilises, run for a further 100 iterations
3. set a new patch inlet velocity
  - back to (1)

- Removes old default behaviour that only permitted an increase in the
  trigger level. This type of 'ratcheting' mechanism (if required) is
  now the responsibility of the derived function object.