v1.3.0

Fixed

• Lines that run off the screen are now clipped the way QBasic clips
  them: one edge at a time, rounding at each step, and drawn from the end
  with the smaller x. New captures from the original showed the old clip
  was out by up to 1777 pixels on lines crossing a corner.
• Circles with a negative aspect, which the gorilla explosion uses, are
  now exactly as flat as the original's: the factor at -1.57 is 0.4297,
  not 0.43.
• The two ends of an arc drawn at a non-default aspect are placed the way
  the rest of the arc is.

Changed

• After every deploy of the browser version, its tests run again against
  the live site.

What's Changed

• Close three test gaps, and check the live site after each deploy by @abedegno in #9
• Close the gaps mutation testing found by @abedegno in #10

Full Changelog: v1.2.0...v1.3.0