v1.4: Modernize project and add MSVC support (#10)

* add .gitignore

* update tests to use doctest

* apply clang-format

* update benchmark and version

* add /permissive- flag

* replace standalone with benchmark test

* add codecov.yaml

* update google benchmark

* update google benchmark

* compile with cross-compilation flags

* test with other flags

* try installing libc++

* try another answer

* also install libc++abi-dev

* build benchmark as release

* remove deprecated std::iterator base class

* why does release build of the benchmark target add the "-Werror" flag?

* require C++17

* add find utility function

* swap argument order

* add instructions to run benchmark