Filter ramping

This fixes https://bugs.launchpad.net/mixxx/+bug/1394839
Both versions are nice for me. It depends on the specific case which is nicer, so I would like to allow both as long we do not have

```
        pState->m_pLowFilter->processAndPauseFilter(
            pLpfInput, pOutput, numSamples);
```  

or this worst one  

```
        for ( loooong
            looong ) {
            do ()
        }
```  
did you get this with your tamplate? 
```
        for ( loooong
             looong ) {
            do ()
        }
```