Causal
A point in history: a namespace state, the causals it was made from, and (not hashed) what made it, when, and
what for, if it was told (message).
export interface Causal { hash: string; namespace: string; parents: string[]; ts: number; command: string; /** what the entry is for, in the words of whoever made it (`-m`): a line, then more after a blank line */ message?: string; }