Replace some deprecated config options.

Author: oleburghardt

_tutorials/multiphysics/steady_cht/Static_CHT.md

@@ -127,13 +127,13 @@ MARKER_ISOTHERMAL= ( core1, 350.0 )
 The solid's material properties are chosen as follows.
 ```
 % Solid density (kg/m^3)
-SOLID_DENSITY= 0.00021
+MATERIAL_DENSITY= 0.00021
 %
 % Solid specific heat (J/kg*K)
-SPECIFIC_HEAT_CP_SOLID = 1004.703
+SPECIFIC_HEAT_CP = 1004.703
 %
 % Solid thermal conductivity (W/m*K)
-THERMAL_CONDUCTIVITY_SOLID= 0.1028
+KT_CONSTANT= 0.1028
 ```
 
 ### Running SU2

_tutorials/multiphysics/unsteady_cht/Inc_Heated_Cylinders_Unsteady.md

@@ -48,7 +48,7 @@ INC_DENSITY_INIT= 0.0210322
 in [flow_cylinder.cfg](https://github.com/su2code/Tutorials/tree/master/multiphysics/unsteady_cht/flow_cylinder.cfg) and
 
 ```
-SOLID_DENSITY= 0.0210322
+MATERIAL_DENSITY= 0.0210322
 ```
 in [solid_cylinder1.cfg](https://github.com/su2code/Tutorials/tree/master/multiphysics/unsteady_cht/solid_cylinder1.cfg), [solid_cylinder2.cfg](https://github.com/su2code/Tutorials/tree/master/multiphysics/unsteady_cht/solid_cylinder2.cfg) and [solid_cylinder3.cfg](https://github.com/su2code/Tutorials/tree/master/multiphysics/unsteady_cht/solid_cylinder3.cfg)