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)

> - Should the Q control for peak filters be inverted?

Now that is a very good question, and one i put some research into while deigning the gui. If we are talking about the handles on the widgets, (right click and move) I total agree they are counter intuitive....

The Resonance knobs caused me a big concern while designing. If it we up to me I would have implemented them as bandwidth, because that is what that knob is changing, and would be more intuitive. First i started by looking at the eq plugins im familiar with, all using resonance, with clockwise increasing, then I looked at few few others that are highly spoke of, they also implemented it the same way.
I am thinking i would rather spend the time, and implement the controls as bandwidth as opposed to just reverse resonance knobs.

@diizy  what's your thoughts on this.

> - For the display widget: how about if you could control the Q/bandwidth
> of each filter by using the scroll wheel while on top of the number?

atm this can be done with right mouse button. but the implementation needs to change. as on the graphic display pulling away from the widget should definitely increase the band width.  I am planning of waiting a couple of weeks while changes are still being made, then i will write some documentation, and possibly a video.


> - Analyzing: how about if you could toggle the display to IN/OUT
> (current), IN only, OUT only? It's sometimes a bit hard to see the curve
> when they're always overlaid, modes to show only in or out would help
> with this. The current IN/Out labels could be used as toggle buttons.

This is a great idea :)



> Also, maybe there could be tooltips/textfloats when moving the number
> widgets on the display - ones that show freq and gain both?

Another good idea. I did try this with fixed labels in the gui, but they took up too much space, so i  removed them.  Why did i not think of using TextFloat. i was even experimenting with them while trying to overwrite the fader text. good call :)