With ankles, the shin stops at the ankle (#174); Aether 0.810.0

[nicolas-maman]

Closes #174. Also moves CI to Aether 0.810.0, the latest release.

The fix

With ankles set, each calf's capsule was built as specified. Its cap reached a radius (8 cm) past the ankle, through the space the foot occupies, and rested on the ground beside the foot.

The shin is now built with its ankle end drawn in by its radius, so its cap ends at the ankle. Unchanged:

• its knee end and radius;
• its spec, so the foot's joint is still made at the ankle;
• a figure without ankles, which keeps the reference's calf.

Standing, with every joint stiff but the ankles soft (the case the issue measured in ae3d), as shares of the figure's weight:

	shins	feet
ankles, capsule as specified	42%	57%
ankles, this PR	0%	100%
no ankles (the reference's)	0%	100%

human_bone_far_end

A built bone's far end in its body's frame:

• a calf with ankles: its ankle, the foot's joint;
• any other bone: the end of its capsule farther from its joint (a forearm's past the wrist, a foot's at the toe).

For ae3d: its bone_far_end takes a calf's ankle from the far end of the shin's capsule. With ankles that end is now a radius short of the ankle, so it should call human.human_bone_far_end.

Tests

test_human has 134 checks, the new ones in test_ankle_shins:

• the shin's shape:
  • its cap ends at the ankle;
  • its knee end and radius are the reference's;
  • without ankles it is the reference's capsule whole;
• the far ends: a calf's, a foot's, a forearm's, and a figure that isn't spawned or an index past its bones;
• the issue's measure, on the table above.

With the shortening disabled, the shape checks fail by 0.08 m and the load checks by 42%.

Pins

• Aether 0.810.0 and aeb v0.326, both the latest releases.
• The gate passes on 0.810.0 before this change too.
• The README's install line had been left at 0.806.0 and now matches CI.