Consider leading:true on debounce

[silverwind]

Currently, there is a useless delay of debounce (default 200ms) before the first onBottom callback which could be avoided by enabling the leading option. This is especially noticeable when one specifies a high debounce like 1000. I see no reason to not set this option, further callbacks can be debounced, but the first should not.

[karl-run]

That's a good point. I'd like not to change any default behaviour but there's no reason why it can't be a prop.

[iwikal]

@karl-run If there isn't any reason to ever want a leading delay, why not change the default behavior? It's hard to imagine well-written code breaking because of such a change.

[karl-run]

Bold of you to assume that most consumers of any library is well written code. 😄

But in any case, I'm more than happy to change the default behaviour and just release a new major version. Anyone want to make a PR?

[karl-run]

This should be fixed now.