add a command for withdraw autominer time

[Cricri6820]

I have a suggestion to add a command for withdraw autominer time, it will be useful for sell this in the auction house when you have a lot of autominer time (like 6 hours)
command syntax: "/am withdraw <time (s|m|h)>" or "/autominer withdraw <time(s|m|h)>" or an other syntax

Here some exemple:
/am withdraw 30s : Withdraw 30 secondes of autominer time
/am withdraw 15m : Withdraw 15 minutes of autominer time
/am withdraw 1h : Withdraw 1 hour of autominer time

[DeadMaster]

Due the server being cracked, people will share their autominer time with their other accounts and have several accounts automining at once.