further normalize floating-point constants

Base/Const/Units.h

Base/Py/PyFmt.cpp

Examples/fit/specular/RealLifeReflectometryFitting.py

Examples/scatter2d/ConstantBackground.py

GUI/Model/Device/BeamItems.cpp

Sample/StandardSamples/FeNiBilayerBuilder.cpp

Tests/Unit/GUI/TestScientificSpinBox.cpp

Tests/Unit/Sample/MultiLayerTest.cpp

Tests/Unit/Sim/ObjectiveMetricTest.cpp