Allow non-zero min in FromPercent

`FromPercent` silently assumed `min` to be 0. Shifting the result by
`min` makes it work as documented and gives a value between `min` and
`max`.

Our uses of `FromPercent` only have `min` at 0, so there is no
regression in our code. This is merely a fix for 3rd party users.

Author: somechris

src/math/FromPercent.js

@@ -22,7 +22,7 @@ var FromPercent = function (percent, min, max)
 {
     percent = Clamp(percent, 0, 1);
 
-    return (max - min) * percent;
+    return (max - min) * percent + min;
 };
 
 module.exports = FromPercent;