Move math.hypot() to misc_helpers.lua and fix zero-division error

builtin/misc.lua

@@ -106,13 +106,3 @@ function minetest.formspec_escape(str)
 	return str
 end
 
-function math.hypot(x, y)
-	local t
-	x = math.abs(x)
-	y = math.abs(y)
-	t = math.min(x, y)
-	x = math.max(x, y)
-	t = t / x
-	return x * math.sqrt(1 + t * t)
-end
-

builtin/misc_helpers.lua

@@ -91,4 +91,14 @@ function minetest.pos_to_string(pos)
 	return "(" .. pos.x .. "," .. pos.y .. "," .. pos.z .. ")"
 end
 
+function math.hypot(x, y)
+	local t
+	x = math.abs(x)
+	y = math.abs(y)
+	t = math.min(x, y)
+	x = math.max(x, y)
+	if x == 0 then return 0 end
+	t = t / x
+	return x * math.sqrt(1 + t * t)
+end