C++17ification!
- Filesystem interaction now uses std::filesystem::path.
- Usage of const char*, std::string have been changed to
std::string_view where appropriate.
- Usage of printf-style functions changed to use fmt.
Function template 'LookupObject' in ObjectTable class has
a specialization in class scope, which is not allowed.
While MSVC seems OK with that, clang complains about it.
Fix this issue by moving the definition of the specialisation
outside the class scope, and moving the declaration in the
'.cc' file.
