Change `userData` type to avoid boxing

[cmann1]

Currently userData is an object, which means that to store a struct or value type it needs to be boxed.
Perhaps it could be changed to an int, long, or pointer?

[ikpil]

That’s a great point. I’ve created a new branch to implement these changes. I’ll give it a try now.

[cmann1]

Looks good, thanks.

[ikpil]

I’ve made the changes and merged them. Could you please take a look?

[cmann1]

Awesome thanks it works perfectly.

Perhaps int/uint overloads for convenience since they're commonly used for indexing arrays?