Add turbocharged twin scenario and cross-platform test harness

include/FluidSim/Crankcase.hpp

@@ -17,6 +17,7 @@ public:
     float temperature() const { return temperature_; }
     float density() const { return mass_ / (volume_ > 1e-12f ? volume_ : 1e-12f); }
     float volume() const { return volume_; }
+    float geometry_work() const { return geometry_work_; } // J delivered by gas during the latest geometry step.
     float mass() const { return mass_; }
     float air_fraction() const { return air_fraction_; }
 
@@ -28,6 +29,7 @@ private:
     Crankshaft& crankshaft_;
     float crank_radius_{}, connecting_rod_length_{}, piston_area_{};
     float clearance_volume_{}, obliquity_{};
+    float geometry_work_{};
     float mass_{}, energy_{}, air_fraction_{1.0f};
     float pressure_{101325.0f}, temperature_{300.0f}, volume_{}, previous_volume_{};