fix(packets): make pinit sub packet unknowns nullable

fix(packets): add missing fields to pinit mate subpacket

Merge pull request #45 from Rutherther/feat/mates

Add support for mates

fix(packets): correctly represent finfo

chore(game): add missing documentation

feat(packets): add party stat packet

feat(packets): add pclear packet

feat(packets): fix pinit packet for various entity types

feat(packets): add many new packets

fix(packets): make correct fields nullable

feat: split packets definitions into separate assembly