• Added rule odigit for octal digits.
• Enabled default-constructed state in state<>, change_state<>, and change_action_and_state<>.
• Changed rules in tao/pegtl/contrib/integer.hpp to not throw by default.
• Added tao/pegtl/contrib/separated_seq.hpp.
• Added tao/pegtl/contrib/iri.hpp grammar for IRIs.
• Added tao/pegtl/contrib/proto3.hpp grammar for protocol buffer v3.