From CppCoreGuidelines:
Rule of Zero: C.20: If you can avoid defining default operations, do.
C.52: Use inheriting constructors to import constructors into a derived class that does not need further explicit initialization.
DRY forward and using declarations.
Miscellaneous:
Fix format.sh to output examples with normalised paths in sorted order.
Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>
Allow Container::Vertical and Container::Horizontal to have an
external selector, similar to Container::Tab.
This is useful for implementing a menu of menu.
Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>