PLAN2D.4 2D smart walls, doors and windows in CadCraft

Asked: "a smart wall tool in cad craft, like a polyline ... choose the thickness ... basic doors and windows that can be inserted into those walls ... it is all 2d, and generates no 3d ... if you move a wall it moves the doors and windows with it ... connects into other walls".

Built in the lab: WALL (thickness, justify, fill, close), DOOR (single, double, sliding, open doorway), WINDOW (fixed, casement, sliding), DELOPENING; mitred corners, T joins, crossings; joined walls follow a move; grips for ends, middle, sliding an opening, flipping hinge and swing; Properties for each opening. A wall is a block carrying its settings, so DWG/DXF, plotting and Move need nothing new; shared engine lib/plan2d (tools/plan2d/sync.mjs).

Not done: wall build-ups (asked as "possibly later"), curved walls, Library doors in these walls, elevations from the plan, not opened in AutoCAD. Dimensions don't attach to walls.