0.18.7

The mockup gate reads a spec's switches however they are spelled, and refuses
icons and images in a drawing's frames.

Fixed

• switches: reads a switch however the spec spells it. jig-site's
  Versions spec wrote switches: [breakpoint-nav]; read as a switch named
  that, it matched nothing, no switch was checked, and the gate passed. nav,
  breakpoint-nav and --breakpoint-nav now name the same switch, and a name
  the project does not record is reported with the ones it does.
• The gate refuses icons and images in a mockup's frames. The procedure
  says an icon is its name in brackets and an image a labelled box; jig-site's
  Versions drawing carried the site's real icons and GitHub's mark, and nothing
  checked. <svg>, <img>, <picture>, <canvas> and icon fonts inside a
  frame now stop the session.