[feat] Ruler element

[toolicious]

A label with a printed scale on it, for a saw fence, a shelf edge or a workbench.

Options:

• mm or inch
• tick interval, plus a longer tick at a bigger one
• numbers on/off and how often
• tick length and thickness
• zero offset and direction (start at 150, or count right to left)

Notes:

• positions via geometry.mmToDots, so the user's feed calibration applies by itself
• ticks run across the tape and print thin, one dot is probably too faint (TestPattern gives its upright border edges an extra dot for this)
• TestPattern already draws a 5/10 mm scale, copy from there
• inch needs 1/8 and 1/16 marks and labels like "3 1/2"
• numbers have to shrink with the head, 30 dots is tight