use less precision, make things prettier?!

and also faster.  magic, kind of.

glsl/raymarching.js

@@ -81,7 +81,7 @@ uniform vec2 iResolution;
uniform vec3 iMouse;
const int MaximumRaySteps = 150;
const float MinimumDistance = 0.0000001;
const float MinimumDistance = 0.0001;
float DistanceEstimator(vec3 pos);