(linear tapering of extrusion rate for the 1st spiral vase layer)
Linear tapering could only be implemented for relative extruder distances.
For absolute extruder distances, all the G1 Exxx in all spiral vase layers
would have to be adjusted, which is much more complex and risky to do now
before release.
above the solid infill. Should fix
first layer of vase (after bottom layers) is bulging (0.6nozzle, 0.4 layerhight) #3712
Adjust flow of the "second" layer in spiral vase mode #2795
Fixes Connecting / expanding Bottom Layers to Vase Perimeter #253
Fixes Slicing error in vase mode #452
Fixes Slicing Issue (Vase Mode, 0.6mm dmr nozzle) #1887
Fixes Top fill pattern isn't used in spiral vase mode #2533
Fixes Cisar's vase doesn't slice correctly, creates artefacts #3595
When the model is sliced, all the contours are newly oriented
counter-clockwise (even holes), merged and then only the largest area
contour is retained. In perimeter generator, if the largest contour
splits into multiple perimeters, newly only the largest area perimeter
is retained in spiral vase mode. These two changes solve #3595 and similar.
The infill is newly calculated only for the bottom solid layers
if the spiral vase mode is active (removes various unwanted infill
along the vase walls), and the last bottom solid layer is switched
to a top solid pattern (solves #2533).
The thin walls are newly enforced to be disabled in spiral vase mode,
and the "ensure vertical shell wall" is enforced in spiral vase mode
to extend the bottom of the vase to the vase hull (fixes#253).
