alimiter: support for compensating for attack-time-delay & side-chain version

[mtc]

1. option to disable/cancel the exact attack-time-offset (similar to firequalizer's zero_phase option)

This limiter uses lookahead technology to prevent your signal from distorting. It means that there is a small delay after the signal is processed. Keep in mind that the delay it produces is the attack time you set.

2. non-offset audio may be required for a side-chain version of alimiter to work properly (similar to sidechaincompress & sidechaingate)

possible use cases: run limiter on up-sampled version of audio and downsample results tp apply to original,
or merging(weighted-average) 2 synchronized audio-samples one with clipping, but louder&clearer, the second one no-clipping but less-clear(quantization&noise)