E-steps calibration chip

This is a variation of [Triffid Hunter's E-steps fine tuning suggestions](http://reprap.org/wiki/Triffid_Hunter%27s_Calibration_Guide#E_Steps_Fine_Tuning).

1. Slice at 95% (rectilinear) infill.
2. Print and then abort the print once only the taller section is printing.
3. Compare top infill (100%), and infill (95%).
- If the top infill has gaps between the lines, increase E-steps by 0.5%-1%.
- If the 95% infill does not have gaps, reduce E-steps by 2%.
4. Repeat from 2.