solutionControl: Renaming and improved final logic

The sub-loops of the solution control are now named more consistently,
with ambiguously named methods such as finalIter replaced with ones
like finalPimpleIter, so that it is clear which loop they represent.

In addition, the final logic has been improved so that it restores state
after a sub-iteration, and so that sub-iterations can be used on their
own without an outer iteration in effect. Previously, if the
non-orthogonal loop were used outside of a pimple/piso iteration, the
final iteration would not execute with final settings.

applications/solvers/basic/potentialFoam/potentialFoam.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -35,7 +35,7 @@ Description
 \*---------------------------------------------------------------------------*/
 
 #include "fvCFD.H"
-#include "pisoControl.H"
+#include "nonOrthogonalSolutionControl.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -76,7 +76,7 @@ int main(int argc, char *argv[])
     #include "createTime.H"
     #include "createMesh.H"
 
-    pisoControl potentialFlow(mesh, "potentialFlow");
+    nonOrthogonalSolutionControl potentialFlow(mesh, "potentialFlow");
 
     #include "createFields.H"