Avoids the clutter and maintenance effort associated with providing the
function signature string.

and two-phase functionality separated from multiphase functionality

Multi-species, mass-transfer and reaction support and multi-phase
structure provided by William Bainbridge.

Integration of the latest p-U and face-p_U algorithms with William's
multi-phase structure is not quite complete due to design
incompatibilities which needs further development.  However the
integration of the functionality is complete.

The results of the tutorials are not exactly the same for the
twoPhaseEulerFoam and reactingTwoPhaseEulerFoam solvers but are very
similar.  Further analysis in needed to ensure these differences are
physical or to resolve them; in the meantime the twoPhaseEulerFoam
solver will be maintained.

This reverts commit c5bea524.

This reverts commit b18f6cc1.

before:
    - 'new' prefixed to camel-cased class name: eg, someClass -> newSomeClass
    - 'New' prefixed to templated class name:   eg, TmplClass -> NewTmplClass
    - 'New' suffixed to class name:             eg, someClass -> someClassNew

after:
    - consistent 'New' suffixed to class name, no change of case
          eg, someClass -> someClassNew
          eg, TmplClass -> TmplClassNew