[BL] ConfigTree using shared_ptr.

Applications/CLI/ogs.cpp

BaseLib/ConfigTree.cpp

BaseLib/ConfigTree.h

BaseLib/ConfigTreeUtil.cpp

BaseLib/ConfigTreeUtil.h

GeoLib/IO/XmlIO/Boost/BoostXmlGmlInterface.cpp

Tests/BaseLib/TestConfigTree.cpp

Tests/MaterialLib/TestCapillaryPressureSaturationModel.cpp

Tests/MaterialLib/TestFluidDensity.cpp

Tests/MaterialLib/TestFluidProperties.cpp

Tests/MaterialLib/TestFluidSpecificHeatCapacityModel.cpp

Tests/MaterialLib/TestFluidThermalConductivityModel.cpp

Tests/MaterialLib/TestFluidViscosity.cpp

Tests/MaterialLib/TestMPL.cpp

Tests/MaterialLib/TestMPLLinearSaturationSwellingStress.cpp

Tests/MaterialLib/TestMPLSoilThermalConductivitySomerton.cpp

Tests/MaterialLib/TestPorousMediumStorage.cpp

Tests/MaterialLib/TestRelativePermeabilityModel.cpp

Tests/MathLib/TestLinearSolver.cpp

Tests/MathLib/TestODESolver.cpp