Mitcad 0.10.0: easier BUILD placement, sections and booleans that survive kernel crashes, threads and spiral stairs as clean solids

BUILD

• Parts go into the nearest component that takes components, so a new
  design needs no component activated first. The first part is placed by
  Enter at the origin or by a plane pick, standing along X, Y or Z.
• The panel grows as the placement needs it, and only usable targets
  highlight. Side placements snap flush with the target's ends and never
  overhang it.

Modelling

• Threads of one profile on a cylinder, including threads whose turns
  meet, are built as single solids, and booleans on them stay fast.
• Spiral stairs with helical stringers join into clean solids. More
  fillet corners and chamfer ends are built.
• Split regions keep all their pieces, and cut pieces keep their ids. The
  Dimension tool sets signed dimensions, also between points.
• Sketches solve coincidences within the tolerance. Sections of bodies
  can be used as sketch curves, and projections follow chains of edges.
• Section Analysis reports a crash inside the geometry kernel as an
  error instead of closing the app. Mesh bodies take part in sections and
  booleans, and building-scale models mesh.

Import

• .rvt projects: stair runs, risers and landings, multistory stair
  copies, rails with their supports, fillets, helix corners and plumb
  ends, trimmed mullions and slab edges.
• Linked planes and curves come in with their own components; cones of a
  tiny angle are read as cylinders.

Automation

• The MCP interface reports failed features, inserts parts, saves and
  opens live documents and sets the camera.

User interface

• The docked sketch palette scrolls, and the Projects tree indents as
  the Browser does.