preliminary improvements for externalCoupled

• added interpretation of lock file contents to function similarly to the abort function object, which allows the slave process to signal OpenFOAM to stop.
• various adjustments to time and residuals control for more flexibility.

changed title from Feature external coupled to Improvements to externaCoupled

changed target branch from master to develop

changed milestone to %v1712

changed title from Improvements to externaCoupled to preliminary improvements for externalCoupled

changed the description

added 1 commit

• 995f23d0 - ENH: add simple subLoopTime

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@landmann

merged

mentioned in commit 93d8ab84