Rename rng_disc() to rng_plusminus()

src/rng.c

@@ -30,14 +30,15 @@ double rng_canon(rng_t *rng)
 	return (double)rng_uint32(rng) / (double)UINT32_MAX;
 }
 
-double rng_disc(rng_t *rng)
+double rng_plusminus(rng_t *rng)
 {
 	return 2.0 * rng_canon(rng) - 1.0;
 }
 
 vec3_t rng_vec3(rng_t *rng)
 {
-	const vec3_t v = { rng_disc(rng), rng_disc(rng), rng_disc(rng) };
+	const vec3_t v
+	    = { rng_plusminus(rng), rng_plusminus(rng), rng_plusminus(rng) };
 	return vec3_unit(v);
 }