wireshark: handle empty of_octets_t
ir: add enum_by_name to OFProtocol
wireshark: pick wireshark type/base based on the oftype and field name
wireshark: add readers for several oftypes
wireshark: read actions list
wireshark: set description of list node to dissector's returned info string

Also remove the type lookup since that's done in the virtual class dissector.