v3.1.8

Release Notes for v3.1.8 since v3.1.6

• implemented adl_relocatable() custom quasi attribute definition for trivially relocatable types, ie relocatable type, that after move in empty state doesn't require destruction even that it doesn't have trivial destructor. (ex: small vectors vectors and strings, std::vector, std::string)
• exploiting use of adl_relocatable in small vectors vectors internal relocations - see uninitialized_relocate* use
• added std::error_code std::formatter
• added std::source_location std::formatter