[FEATURE]Automine and speedmine better feature

[AlexanderJonny]

In fact, on less strict anarchy servers, speedmine is able to do a double slient break.
The client shown in the video, which we call "madcat"
The function shown in the video we call "doublebreak"
In 3arthh4ck, if I set speedmine-damage to 0.0, then I can do the effect in the video, but he can't do the "doublebreak".

speedmine's FEATURE
Add slient doublebreak

automine FEATURE,
With speedmine on doublebreak, automine calculates 2 squares at the same time when doing digging, that is, digging 2 places at the same time.
I hope 3arthqu4ke you can add this feature to earthhack, these features would be very useful in not strictly anarchic servers
watch this https://youtu.be/PPyBJlOk2Ek