Double Precision Y GT2, Printrbot Simple

This is an extension of my 300mm No Sag, that converts to double precision. Check the notes on the source MXL Double precision about speed limits.
I am running this on my machine since early May 2014, but have converted to 1/4 microstep instead of 1/16 microstep. This allows me greater speed and keeps the quality.
I am short on time so the documentation is poor. Any questions please feel free to ask and I will comment when possible.

2014-07-03: I have converted back to 1/16 microstep (