Minor clean-up

Replaces LTSReactingParcelFoam and LTSCoalChemistryFoam

    Select LTS via the ddtScheme:

        ddtSchemes
        {
            default         localEuler rDeltaT;
        }

Relaxation and solution parameters for the final iteration in PIMPLE loops are
now selected according to the value of the "finalIteration" entry in the
mesh::data dictionary.

rhoPimpleFoam significantly updates and now replaces rhoPisoFoam.

uniformDimensionedVectorField.