Inspired by : (A*), (perlin)
Stage 0; perlin works, pathing works... think it cheats and doesn't find a 'best'; continues with backscan after completion (fast complete)
Stage 1; path is by slope; going up is harder than going down... does a wide scan; h1() is too short
Stage 2; path is by height; it prefers to take the lowest path available. (started tracking known 'paths')
Stage 3; Path is by slope. black->blue->red->white is height, and prefer least 'up' path.
Stage 5; Path is by slope. Natural Terrrain colors is height, and prefer least 'up' path.

Perlin Animation Tinker
Perlin 3D Noise evolution