Feature: add multiple publish requests

[sharpfuryz]

Feature: this code allows to push multiple publish operation without mutex lock/unlock which improves performance if you need to send a lot of different messages into different channels.

[sharpfuryz]

@FZambia please review

[FZambia]

Hello @sharpfuryz

It seems to me that the overhead of mutex should be negligible here, especially since there should not be any lock contention. Probably what you really need is a way to create a Pipe with preallocated capacity of commands slice?