* fixed some CLion "Unused global declaration" warnings
* fixed some CLion "Not implemented function" warnings
* fixed some CLion "Unused struct" warnings
* added TODO
* removed unused parameter reported by CLion
* fixed some CLion "Unused macro" warnings
* fixed some CLion "Condition is always true" warnings and a CLion "The value is never used" warning
* added `Settings::useSingleJob()` and use it instead of checking `jobs` or `jointSuppressionReport`
* extracted single job execution into `SingleExecutor`
* moved `reportStatus()` from `CppCheckExecutor` to Èxecutor
* TestSingleExecutor: improved tests
* added testing of markup extension handling in executors
* cleaned up includes based on `include-what-you-use`
* testsingleexecutor.cpp: suppress `performance-unnecessary-value-param` clang-tidy warnings
* ProcessExecutor: send color via pipe instead of applying it beforehand
* do not unconditionally apply colors to output / disable all colors in tests / adjusted tests for changed output behavior
* fixed precision loss in `Executor::reportStatus()`
* fixed `naming-varname` selfcheck warnings
Oliver Stöneberg
Daniel Marjamäki
chrchr-github
orbitcowboy
Paul Fultz II