To deal potential z scaling when fade is enabled, a fade_target option has been introduced. This option may either be set to 0.0 or any z position within the range of the mesh. A value of 0.0 will result in previous behavior, where z adjustment phases out until no further adjustment is added. A non-zero value will phase out adjustment until the target has been reached, after which the rest of the print will be offset along the z axis by the fade_target. By default the fade_target will be calculated as an average of the mesh.
Signed-off-by: Eric Callahan <arksine.code@gmail.com>