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superceded,\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,\
"
```
25 jobs for !5040 with fix-typos-identified-using-codespell in 51 minutes and 2 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Build
passed #5093643
linux docker build manual
build:centos6-release

00:04:52

passed #5093640
linux docker build
build:debian10-iwyu

00:02:25

passed #5093644
linux-3.17 linux docker build manual
build:fedora31-ninja

00:01:09

passed #5093642
linux-3.17 linux docker build
build:fedora31-sphinx

00:03:53

passed #5093641
linux-3.17 linux docker build
build:fedora31-tidy

00:03:26

passed #5093646
nonconcurrent xcode-11.5 shell macos cmake manual
build:macos-makefiles

00:02:09

passed #5093645
nonconcurrent xcode-11.5 shell macos cmake manual
build:macos-ninja

00:02:35

passed #5093647
nonconcurrent msvc-19.25 vs2019 shell windows cmake manual
build:windows-vs2019-x64-ninja

00:06:33

 
  Test
passed #5093648
linux-3.17 linux docker build
test:fedora31-ninja

00:03:25

passed #5093650
nonconcurrent xcode-11.5 shell macos cmake
test:macos-makefiles

00:20:29

passed #5093649
nonconcurrent xcode-11.5 shell macos cmake
test:macos-ninja

00:07:38

passed #5093651
nonconcurrent msvc-19.25 vs2019 shell windows cmake
test:windows-vs2019-x64-ninja

00:18:33

 
  Test Ext
passed #5093653
linux docker cuda-rt
test:cuda10.2-nvidia

00:01:20

passed #5093652
linux-3.17 linux docker build
test:fedora31-makefiles

00:17:24

passed #5093654
linux-3.17 linux docker build
test:fedora31-ninja-multi

00:03:10

passed #5093655
concurrent xcode-11.5 shell macos cmake
test:macos-xcode

00:29:43

passed #5093656
concurrent msvc-19.25 vs2019 shell windows cmake
test:windows-vs2019-x64

00:18:10

 
  External
passed cdash

passed ghostflow-check-master

passed ghostflow-stager

passed cdash

passed cdash

passed cdash

passed ghostflow-stager

passed ghostflow-stager