I need to add parameters to some `check()` functions in the tests and
things are already pretty messy with having to specify all the default
values - readability aside.
I found this on https://stackoverflow.com/a/49572324/532627 - apparently
the CC BY-SA license by StackOverflow allows the usage within GPL.
* 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
Oliver Stöneberg
Paul Fultz II
Daniel Marjamäki