set viewport to speed up mobile taps, hex and square both handle 'pointy top' versions

src/utils.js

@@ -31,6 +31,13 @@ export function extend(obj, src) {
 	return obj;
 }
 
+// hypotenuse factor of isoscelese right triangle
+export let sqrt2 = Math.sqrt(2);
+
+// short width factor given the lenght of a hexagon's side
+// (2*S gives long width)
+export let sqrt3 = Math.sqrt(3);
+
 export function hypotenuse(a, b) {
 	if (b == null) b = a;