Keep side-view half circles clear of strips and name turns by crease

[tophcodes]

Refs #232

Keeps the half circles of the side view clear of the strips and names each turn after the crease the program names.

Layout. Along the line the section keeps the proportions of the paper, with one scale for the whole line, so places that lie above one another in the folded state lie above one another in the section; no strip moves along the line. A turn is a half circle on the place of its hinge, from the end of one strip to the end of the other, bulging out past them, with a radius of half the height between the two, as before #233. Where a half circle would cross a strip or the half circle of another place, the layers move closer, 2 px at a time from 34 px down to 22 px; where that is not enough, the line grows longer at the same scale, up to three times. Where turns open to both sides of one place, the section opens a gap there for both, as before #233, since the half circles of one side would otherwise cover the strips that end there from the other side at every pitch. The section grows wider than 572 px where turns bulge out past the ends of the line. A test checks on six fixtures that no strip lies inside a half circle.

Names. A folded hinge on a crease the program names carries the name the FOLD file records for its edge, written as the program writes it (--q). It stands once for each crease at one place and side, outside the outermost turn there, and moves down where it would overlap a name placed before it. Hinges on unnamed creases carry none. A test folds a sheet along --d and again along an unnamed crease and finds --d alone.

Numbers. A strip's number stands over its part, short of the part's end; where it would overlap the number before it on its level, the number moves right.

spec/CLI.md states the layout and the names.

issue-assets redraws the side views of #203 and #205; #230 links the new #205 files.

The frog after both sides of step 13, before:

After: