Allow overly large buffers for chunk filtering

[petiaccja]

The size of the output buffer should be allowed to be larger than the input buffers, this makes it easy to include the fade-out when the signal runs out. Alternatively, one could feed an all-zero signal as input, but why create another signal just for that?

[petiaccja]

It's actually quite error-prone to allow larger signals. At the moment, a size mismatch is met with an exception, whereas with arbitrarily large outputs mismatched chunks would be silently accepted.

Possible solutions:

• add a new FilterTail function (cannot overload)
• add overload to Filter with magic type Zeros{ n }
• implement a signal-like lazy generator

I'll close this for now as it's still fairly easy to just feed an all-zero signal