Typos and spelling errors in source, documentation and scripts

[warmsocks]

Description

When I added doctest.h to a project, I did a spelling check prior to commit. Codespell flagged a handful of spelling errors in the file, which I would prefer not to propagate. I then ran codespell on the whole doctest repo and it found additional ones.

Steps to reproduce

1. Install codespell using pip. Instructions are at the codespell repo here: https://github.com/codespell-project/codespell
2. Run codespell at the head of the doctest repo with the command codespell -q 7 .
3. Observe the following typos/spelling errors reported in the repo:

./CHANGELOG.md:111: endianess  ==> endianness
./CHANGELOG.md:253: lastest  ==> latest
./CHANGELOG.md:425: dont  ==> don't
./scripts/cmake/doctestAddTests.cmake:57: commans  ==> commands
./.github/pull_request_template.md:13: thats  ==> that's
./doc/html_generated/commandline.html:30: atleast  ==> at least
./doc/html_generated/features.html:19: aggresive  ==> aggressive
./doc/html_generated/logging.html:12: heterogenous  ==> heterogeneous
./doc/html_generated/faq.html:87: yelds  ==> yields
./doc/html_generated/parameterized-tests.html:34: doesnt  ==> doesn't, does not
./doc/html_generated/roadmap.html:151: begining  ==> beginning
./doc/html_generated/strapdown.js/strapdown.js:182: occured  ==> occurred
./doc/html_generated/strapdown.js/strapdown.js:199: isnt  ==> isn't
./doc/html_generated/strapdown.js/strapdown.js:259: nd  ==> and, 2nd
./doc/html_generated/strapdown.js/strapdown.js:421: dont  ==> don't
./doc/html_generated/strapdown.js/strapdown.js:426: informations  ==> information
./doc/html_generated/strapdown.js/strapdown.js:466: dont  ==> don't
./doc/markdown/commandline.md:25: atleast  ==> at least
./doc/markdown/roadmap.md:146: begining  ==> beginning
./doc/markdown/faq.md:82: yelds  ==> yields
./doc/markdown/parameterized-tests.md:29: doesnt  ==> doesn't, does not
./doc/markdown/logging.md:7: heterogenous  ==> heterogeneous
./doc/markdown/features.md:14: aggresive  ==> aggressive
./examples/all_features/test_cases_and_suites.cpp:54: overrided  ==> overridden
./examples/all_features/test_output/order_1.txt:31: overrided  ==> overridden
./examples/all_features/test_output/filter_2_xml.txt:81: overrided  ==> overridden
./examples/all_features/test_output/test_cases_and_suites.cpp.txt:46: overrided  ==> overridden
./examples/all_features/test_output/test_cases_and_suites.cpp_xml.txt:61: overrided  ==> overridden
./examples/all_features/test_output/order_1_xml.txt:41: overrided  ==> overridden
./examples/all_features/test_output/order_2.txt:91: overrided  ==> overridden
./examples/all_features/test_output/order_2_xml.txt:98: overrided  ==> overridden
./doctest/doctest.h:750: retreived  ==> retrieved
./doctest/doctest.h:4227: dont  ==> don't
./doctest/doctest.h:5371: begining  ==> beginning
./doctest/doctest.h:5371: occurance  ==> occurrence
./doctest/parts/doctest.cpp:1593: dont  ==> don't
./doctest/parts/doctest.cpp:2737: begining  ==> beginning
./doctest/parts/doctest.cpp:2737: occurance  ==> occurrence
./doctest/parts/doctest_fwd.h:747: retreived  ==> retrieved

Extra information

I'll submit a PR with a fix for all of these except the ones in strapdown.js, since those should be fixed upstream.

• doctest version: v2.3.4
• Operating System: CentOS Linux release 7.6.1810 (Core)
• Compiler+version: g++ (GCC) 8.3.1 20190311 (Red Hat 8.3.1-3)

[onqtam]

some of those should certainly be fixed, but some are in 3rd party source code... I wouldn't mind a PR to the dev branch :)