potentialFoam: Solve for velocity potential named Phi rather than using the pressure field for this purpose

The Phi field is read if available otherwise created automatically with
boundary conditions obtained automatically from the pressure field if
available (with optional name) otherwise inferred from the velocity
field.  Phi Laplacian scheme and solver specification are required.  See
tutorials for examples.

tutorials/heatTransfer/chtMultiRegionSimpleFoam/heatExchanger/system/air/topoSetDict.1: further correction to avoid duplicate registration

GeometricField: Do not transfer registration of a GeometricField to a copy unless it is being transferred from a tmp
This avoids loosing the registration of non-tmp fields

Use interFoam with fvOptions

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1348

Fix provided by Mattijs Janssens

Resolves bug-report http://openfoam.org/mantisbt/view.php?id=1382

tutorials/lagrangian/reactingParcelFilmFoam/hotBoxes/patchifyObstacles: another change to avoid duplicate registration

Required change to IOobjectList to support the optional no-registration specification

tutorials/lagrangian/reactingParcelFilmFoam/hotBoxes: Avoid using the same same for different objects in setSet

thermophysicalModels: Don't register derived fields such as Cp to avoid name conflicts in the objectRegistry

Updated mesh-motion functionality

Explicitly name derived fields to improve readability of diagnostic messages and avoid duplicate registration

Avoids problem of duplicate registration

twoPhaseEulerFoam/twoPhaseSystem/diameterModels/constantDiameter: Do not register the temporary diameter field