KerfScript 0.2.0

First public release.

• render() returns paths (path data per layer), width and height, and
  every sheet has paths, so host apps can draw layers without parsing SVG.
  Each layer path has d (everything), regions (closed outlines, filled
  even-odd on fill layers) and lines (open lines, always stroked).
• margin render option and --margin flag: space between the parts and
  the sheet edge, separate from gap between parts (defaults to gap).
• Errors from a missing font carry missingFonts, so a host can load the
  fonts and render again.
• parameters() gives list settings "type": "number" with a list
  initial, the same as OpenSCAD's parameter JSON (was "vector").
• Every setting has span, the source offsets of its value, so an editor
  can change the value without touching anything else.
• A setting's caption comes only from a comment on its own line above it,
  not from the end-of-line comment of the setting before.
• text_width() and text_metrics() errors report their line and column.
• A warning when kerf compensation closes a hole narrower than the kerf.
• kerf check lists every sheet with its material, thickness and pieces;
  kerf render warns when several sheets are stacked in one SVG, and
  kerf --version shows the language version too.
• Guides in docs/, calibration square and kerf test examples, and
  npm run compat, which checks SVG and DXF output in Inkscape.