Added the pressure dependent part of the entropy from the equation of
state to that returned by the thermo entropy function.

TODO: Add entropy defect to the PengRobinsonGas::s(p, T) function.

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1411

    fixing bug in hExponentialThermo. Updating oppositeBurningPanels tutorial.

Rationalised "make" macros to reduce code duplication
Removed solid phase radiation properties
Updated tutorials appropriately

New base class for fluid and solid thermo: veryBasicThermo
Base class for fluid thermo: basicThermo (derived from veryBasicThermo)
Base class for solid thermo: solidThermo (derived from veryBasicThermo)

Note in next commit basicThermo -> fluidThermo, veryBasicThermo -> basicThermo

This reverts commit c5bea524.

This reverts commit b18f6cc1.

pointSolidMixture. chtMultiRegion tutorials and solvers