Support low delays for high number of stages

[jpcima]

A current limitation : the frequencies of clocks which drive BBD must be under the Nyquist frequency.

Since delay is inversely proportional to clock frequency, and clock frequency is limited by sample rate, higher stage counts such as >=4096 don't have access to the low enough delays that a chorus needs.

A solution is possibly to run the BBD and its clock oversampled, but it multiplies usage of CPU. From the minimal Nyquist (22050 Hz) to a nonimal maximum clock of 100 kHz, this would take an oversampling x5.

(need to think if more optimized solution is possible)