Fix typos identified using codespell

See https://github.com/codespell-project/codespell#readme

The following command was used:

```
codespell -q6 --skip="\
.git,\
*.json,\
./Copyright.txt,\
./Help/command/foreach.rst,\
./Help/prop_test/REQUIRED_FILES.rst,\
./Help/variable/CTEST_COVERAGE_COMMAND.rst,\
./Modules/CMakeCheckCompilerFlagCommonPatterns.cmake,\
./Modules/CMakeRCInformation.cmake,\
./Modules/Internal/CPack/NSIS.template.in,\
./Modules/FindMatlab.cmake,\
./Modules/MatlabTestsRedirect.cmake,\
./Modules/Platform/Windows-Clang.cmake,\
./Modules/Platform/Windows-Intel-Fortran.cmake,\
./Modules/Platform/Windows-MSVC.cmake,\
./Source/CMakeVersion.cmake,\
./Source/cmConvertMSBuildXMLToJSON.py,\
./Source/cmCreateTestSourceList.cxx,\
./Source/cmGlobalVisualStudio10Generator.cxx,\
./Source/cmExportBuildFileGenerator.cxx,\
./Source/cmExportInstallAndroidMKGenerator.cxx,\
./Source/cmExportInstallFileGenerator.cxx,\
./Source/cmExportSet.cxx,\
./Source/cmExportTryCompileFileGenerator.cxx,\
./Source/cmFindPackageCommand.cxx,\
./Source/cmInstallCommand.cxx,\
./Source/cmGeneratorExpressionLexer.cxx,\
./Source/cmLocalVisualStudio7Generator.cxx,\
./Source/cmOrderDirectories.cxx,\
./Source/cmTarget.cxx,\
./Source/kwsys/*,\
./Source/QtDialog/CMakeSetupDialog.ui,\
./Source/CPack/WiX/cmWIXRichTextFormatWriter.cxx,\
./Source/CTest/cmParseCoberturaCoverage.h,\
./Tests/CMakeTests/ImplicitLinkInfoTest.cmake.in,\
./Tests/RunCMake/CPack/tests/DMG_SLA/English.license.rtf,\
./Tests/RunCMake/CPack/tests/DMG_SLA/German.license.txt,\
./Tests/RunCMake/CPack/tests/DMG_SLA/German.menu.txt,\
./Tests/RunCMake/GoogleTest/xml_output.cpp,\
./Tests/RunCMake/Make/TargetMessages*,\
./Utilities/*,\
" \
-L "\
dependees,\
endwhile,\
fo,\
filetest,\
helpfull,\
nd,\
objext,\
stoll,\
supercedes,\
superceded,\
vas,\
varn,\
"
```
35 jobs for !5040 with fix-typos-identified-using-codespell in 2 minutes and 49 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Build
manual #5094280
linux docker build manual
build:centos6-release
passed #5094277
linux docker build
build:debian10-iwyu

00:01:33

manual #5094281
linux-3.17 linux docker build manual
build:fedora31-ninja
passed #5094279
linux-3.17 linux docker build
build:fedora31-sphinx

00:02:49

passed #5094278
linux-3.17 linux docker build
build:fedora31-tidy

00:02:24

manual #5094283
nonconcurrent xcode-11.5 shell macos cmake manual
build:macos-makefiles
manual #5094282
nonconcurrent xcode-11.5 shell macos cmake manual
build:macos-ninja
manual #5094284
nonconcurrent msvc-19.25 vs2019 shell windows cmake manual
build:windows-vs2019-x64-ninja
 
  Test
created #5094285
linux-3.17 linux docker build
test:fedora31-ninja
created #5094287
nonconcurrent xcode-11.5 shell macos cmake
test:macos-makefiles
created #5094286
nonconcurrent xcode-11.5 shell macos cmake
test:macos-ninja
created #5094288
nonconcurrent msvc-19.25 vs2019 shell windows cmake
test:windows-vs2019-x64-ninja
 
  Test Ext
created #5094290
linux docker cuda-rt
test:cuda10.2-nvidia
created #5094289
linux-3.17 linux docker build
test:fedora31-makefiles
created #5094291
linux-3.17 linux docker build
test:fedora31-ninja-multi
created #5094292
concurrent xcode-11.5 shell macos cmake
test:macos-xcode
created #5094293
concurrent msvc-19.25 vs2019 shell windows cmake
test:windows-vs2019-x64
 
  External
passed cdash

passed ghostflow-check-master

passed ghostflow-stager

passed cdash

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager