Mesh filtering edition

merged against slic3rPE1.42.0-alpha7

new

• new tab & icon for the setting, some option have changed place.
• Curve smoothing (slicing tab): an experimental option to try to smooth curve by applying a Bezier curve where a point has a specific angle against the neighbours. These point are the intersection of the polygons's edges and the slicing plane. This may allow you to export a rough cylinder and print an extremely smooth one. Be careful, as it only work on layers, don't use a low angle threshold (160 max is recommended). Will do a wiki on that later.
• Model rounding precision (slicing tab): Now, slic3r remove colinear points, to simplify the input geometry by removing points/edges that are on a middle of a plane (so they are useless). The setting allow some deviation from the plane. So a plane that should be flat but isn't because of the rounding precision of the stl file, now can be flat again.
• skirt & brim are no per-object when you select "compete individual object" #48 bugfix in next version
• no perimeter on bridge area: reworked
  • Remove perimeters: remove the unsupported perimeter, let the bridge area as-is."
  • Keep only bridges: remove the unsupported perimeter, kep only bridges that end in solid area."
  • Keep bridges and overhangs: remove the unsupported perimeter, keep only bridges that end in solid area, fill the rest with overhang perimeters+bridges."
  • Fill the voids with bridges: remove the unsupported perimeter, draw bridges over the whole hole. !! can lead to problems with overhangs shape like /\, consider carefully before using this option!"

##bugfix

• #52 #47 #48 #45
• gyroid & 3d honeycomb now doesn't produce incoherent connecting lines anymore.
• gyroid & 3d honeycomb have more connected line, it's not perfect yet (wip)
• now the settings have a better label when selected in the contextual / right menu.

notes

I may add here a bugfix-only 1.42.0-alpha5.3 in some days