Fuck yeah boids

• Cursor is both an avoid-zone and scares landed boids.
• Walls (screen edges) are normal walls.
• HTML elements classed boids_avoid (and the cursor) get surrounded by fences, fences are not walls, the closer a boid gets to a (actually, to the closest) fence, the stronger it'll change course to avoid the fence, while maintaining velocity. If the swarm isn't too crowded, they should flow around the cursor, and fences.

• TODO

  • Flappy boids, something based on sin(accumulated_boid_accel).
  • Follow SIGWINCH.
  • Should make walls probably go away again, and use old-school "if the boid is off-screen, push it towards center of screen" semantics. Yet I kinda like the idea that boids can escape your gaze and be free, out there, infinite plain.
  • Let the fuck go! As always I'm approaching this way too deterministically but this thing is a fountain of emergement behaviour (including uncool things like getting stuck) and I should at a certain point soon step the fuck back and let the dead digitized birds fall as they may.