More visualizers

I've added two more visualizers with colors. I took the coloring code from this pull request https://github.com/arybczak/ncmpcpp/pull/7, so that should probably be merged first.

The ellipse visualizer was inspired by consolecandy http://vanheusden.com/consolecandy/

Ellipse:

![alt text](http://i.imgur.com/rzVkymQ.gif "Ellipse")


Wave filled:

![alt text](http://i.imgur.com/ja9ziEu.gif "wave_filled")