Retract Before Outer Wall
====
When moving to an outer wall, this setting orders the printer to always retract, in order to reduce blobs on that outer wall.

When the nozzle needs to travel, the material can ooze out of the nozzle a little bit. This oozed material tends to end up on the wall where it enters. For the outer wall this is particularly annoying since the blob will be visible on the outside. This setting is intended to prevent this from happening, because when the material is retracted during the travel move, the material will ooze less.

On the flip side however, this does require the material to be unretracted when the desired position on the outer wall is reached. During this unretraction the nozzle stands still for a split second, which leads to a blob as well because the material does ooze and the material of the outer wall can melt.