Create CI environment to test compatibility with C++98

[palemieux]

Modern platforms require C++ > 98.

CI should include testing in an environment that uses C++98, i.e. __cplusplus <= 199711L

Suggest running the environment in a Docker container and requiring C++98 using the CMake directive: set_property(TARGET ${PROJECT_NAME} PROPERTY CXX_STANDARD 98)

Spawned from #151