Linear advance guide - Free and easy print quality improvement

Linear advance is a firmware feature that controls the timing of the extruder separate to the other axes, with a focus on managing pressure inside the nozzle. The result should be more consistent extrusion, especially around corners and other changes of direction. You should also be able to print faster without the quality dropping off so much. This great feature was introduced into Marlin by Sebastianv650, and once enabled in the firmware, is tuned visually by inspecting a calibration pattern to find the