Support G10/G11 retraction/recover commands.
Marlin now supports G10 and G11, which allows the firmware to control the retraction and recovery distances and speeds, as well as Z-lift if needed. While there is also a feature to try to detect slicer-inserted retraction/recovery code and replace it with the firmware settings, it will be far more reliable if the slicer is aware and participates. Slic3r has support for generating G10/G11 in place of slicer-generated retraction code, it would be great for Simplify3D to do this as well. This is an early but important step towards enabling greater independence between machine specific settings and the resulting G-code.
