Address cppcheck reports
On my macOS (cppcheck 1.85) I got ~1680 check_fails:
- 360 syntax errors on TEST/TEST_F
- 205 no explicit constructors
- 881 missing overrides
- 47 various styles (e.g. use STL algorithm, no copy constructor, no operator eq, variable scope)
- 69 information (e.g. unmatched suppression, configuration not checked, too many configs)
- 38 passed by value performance hints
- 14 various performance hints (use initialization list, postfix operator, STL string find)
- 26 duplicated inherited member warnings
- 20 virtual call in constructor warnings
- 15 null pointer warnings
- 11 uninitialized member variable warnings
- 1 identical condition after early exit warning
- 1 identical inner condition warning