Save hashes of displayed comments locally and mark new ones when displayed for the first time
Initial explorative experiment; works but I am not sure about resources cost.
Saves hashes of once displayed items at The Orange Site to localStorage and highlights those displayed for the first time. (Each displayed post link and comment gets 28 bytes long SHA-1 hash when stays in viewport for 900 ms.)
Useful for tracking heavily branched discussion or spot new top post among others.
