Merge topic 'add-extra-boolean-comparisons'

Help/command/if.rst

Help/command/string.rst

Help/manual/cmake-generator-expressions.7.rst

Help/release/dev/add-extra-boolean-comparisons.rst

Help/variable/CMAKE_VERSION.rst

Source/cmCTest.cxx

Source/cmConditionEvaluator.cxx

Source/cmGeneratorExpressionNode.cxx

Source/cmStringCommand.cxx

Source/cmSystemTools.cxx

Source/cmSystemTools.h

Tests/CMakeTests/VersionTest.cmake.in

Tests/CTestTestStopTime/GetDate.cmake

Tests/Complex/CMakeLists.txt

Tests/Complex/Executable/complex.cxx

Tests/Complex/VarTests.cmake

Tests/ComplexOneConfig/Executable/complex.cxx

Tests/ComplexOneConfig/VarTests.cmake