WIP: added a fakenews library with a vinyl~ filter (gsoc)

I have added a fakenews library in externals for a potential gsoc proposal. At the moment, there is only a vinyl~ filter which uses a IIR low shelf filter to implement a "warm" sound of vinyl.

There are still work to be done to implement further effects to imitate the vinyl sound (e.g. adding vinyl "crackling" sound as well as using a high shelf filter to reduce the amplitude of high frequency components).

Any feedback is much appreciated.