Fixed typos / spelling, in comments only

Accelerators/Vtkm/Core/vtkmDataArray.h

Accelerators/Vtkm/Core/vtkmlib/vtkmDataArray.hxx

CMakeLists.txt

Charts/Core/Testing/Cxx/TestBoxPlot.cxx

Charts/Core/vtkChartXY.cxx

Charts/Core/vtkPlotHistogram2D.h

Charts/Core/vtkScatterPlotMatrix.cxx

Common/Core/SMP/STDThread/vtkSMPThreadPool.cxx

Common/Core/SMP/STDThread/vtkSMPThreadPool.h

Common/Core/Testing/Cxx/TestValueFromString.cxx

Common/Core/Testing/Cxx/UnitTestMath.cxx

Common/Core/vtkAffineImplicitBackend.h

Common/Core/vtkCompiler.h

Common/Core/vtkConstantImplicitBackend.h

Common/Core/vtkImplicitArray.h

Common/Core/vtkInformationObjectBaseVectorKey.cxx

Common/Core/vtkInherits.h

Common/Core/vtkMatrixUtilities.h

Common/Core/vtkTypedDataArrayIterator.h

Common/Core/vtkValueFromString.cxx