added example of a bug when the parent element has an offset and impleme...

...nted solution

There's a problem when the avatar's parent element is `<position:absolute>` or `<position:relative>` and has a `<top>` or `<left>` etc that is non-zero. This causes the avatar to be offset from the mouse cursor by that same amount. I have put an example of this in the examples directory under parentOffsetBug.

At least for my own purposes, it was enough to append the avatar to the `<document.body>` instead of to the immediate parent. This solves the problem for my uses but I'm not sure if it's the best solution for all cases. It seemed reasonable to me that because the avatar was meant to be a temporary object, it doesn't matter too much where in the document it was attached.