Better colaboration support

[Yurab0b]

The current collaboration method - Shuffle tasks, is very inefficient, because most of the time you're just breaking the same block

My suggestion is to generate a "seed" that is used to determine which blocks to break and place on one client and share it with the second client automatically by /msg <header (to inform that its a seed for HT)> <seed>

the second client uses that to know what blocks the first client will be placing & breaking and it uses that to know which blocks to break without interfering with the first client

note: the seed + header should be less then 32 charecters of ASCII due to some servers having strict chat filters