As we'll be creating a deeper hierarchy of modules subordinate to
layout, we need to keep the module full paths short to prevent tem from
growing uncontrollably.
The term "component" has already a meaning in electronics, and moreover
the term "connected component" from graph theory may apply to more
things (e.g. landmasses made of continents connected with bands may
collectively be considered connected components too).
- "connected" is renamed to "joined" (more local term),
- primitives whose clearance area neighbors another's are now called
"abutters",
- primitives whose geometries depend on a bend are now called
"posteriors" of said bend.