Color Mixer for RAMPS

Did you ever want to have rainbow prints ?
This Thing adds a knob to your printer where you can change the colormix ration of your
printer right during printing. So if you use yellow and blue filament, you can select to use
*any* green color during print, and you can change the ratio instantiously at any Z level.

To realize this you need

* Arduino Ramps based printer
* Source code and Arduino Compiler in place
* Chimera dual color nozzle
* Dual extruder setup
* 10K Potentiometer