Thermodynamics: Changed all eEqn to EEqn and reformulated to conserve E in sonic solvers

To support these changes the need for "Sp" corrections on div-terms has been
eliminated by introducing a "bounded" convection scheme which subtracts the Sp
term from the selected scheme.  The equivalent will be needed for the ddt term.

A warning message is generated for steady-state solvers in which the "bounded"
scheme is not selected for the convection terms.

etc/controlDict

@@ -884,6 +884,7 @@ DebugSwitches
     wallHeatTransfer    0;
     wallLayerCells      0;
     wallModel           0;
+    warnUnboundedGauss  1;
     waveTransmissive    0;
     wedge               0;
     weighted            0;