Eq plugin

Initial pull request for the native EQ plugin, #1376 

![image](https://cloud.githubusercontent.com/assets/7412852/5425560/4ecbfbbc-8314-11e4-9a7e-334e7910f87e.png)

> why are you calling the setFrequency and setQ calls every period?

The EqFilter::setFrequency, setSampleRate, setQ, and setGain, all check if there vaules change before calculating coefficents.



> you should probably consolidate setFreq and setQ into one function

good idea :)