chemistryModel: new general chemistry solver created by merging standardChemistryModel and TDACChemistryModel

To simplify maintenance and further development of chemistry solution the
standardChemistryModel and TDACChemistryModel have been merged into the single
chemistryModel class.  Now the TDAC mechanism reduction and tabulation
components can be individually selected or set to "none" or the corresponding
entries in the chemistryProperties dictionary omitted to switch them off thus
reproducing the behaviour of the standardChemistryModel.

For example the following chemistryProperties includes TDAC:

    #includeEtc "caseDicts/solvers/chemistry/TDAC/chemistryProperties.cfg"

    chemistryType
    {
        solver            ode;
    }

    chemistry       on;

    initialChemicalTimeStep 1e-7;

    odeCoeffs
    {
        solver          seulex;
        absTol          1e-8;
        relTol          1e-1;
    }

    reduction
    {
        tolerance   1e-4;
    }

    tabulation
    {
        tolerance   3e-3;
    }

    #include "reactionsGRI"

and to run without TDAC the following is sufficient:

    chemistryType
    {
        solver            ode;
    }

    chemistry       on;

    initialChemicalTimeStep 1e-7;

    odeCoeffs
    {
        solver          seulex;
        absTol          1e-8;
        relTol          1e-1;
    }

    #include "reactionsGRI"

or the "reduction" and "tabulation" entries can be disabled explicitly:

    #includeEtc "caseDicts/solvers/chemistry/TDAC/chemistryProperties.cfg"

    chemistryType
    {
        solver            ode;
    }

    chemistry       on;

    initialChemicalTimeStep 1e-7;

    odeCoeffs
    {
        solver          seulex;
        absTol          1e-8;
        relTol          1e-1;
    }

    reduction
    {
        method      none;
        tolerance   1e-4;
    }

    tabulation
    {
        method      none;
        tolerance   3e-3;
    }

    #include "reactionsGRI"

etc/codeTemplates/dynamicCode/basicChemistryModel

@@ -27,8 +27,7 @@ solverRenamed
 
 method
 (
-    standard
-    TDAC
+    chemistryModel
 );
 
 codeOptions