two_billion_rows example scrolls no less than ~2000 rows at a time

Not sure if this is a bug, or intended behavior (or if I'm just missing something obvious).

### Steps to Reproduce:
Clone this repo, then:

```
yarn install
yarn start
```

then navigate to the two_billion_rows example.

### Expected Result:

For the example to only scroll 1 row at a time (I guess? That might not be the best behavior either) for every press of the up/down keys or tic of the scroll wheel.

### Actual Result:

I was playing around with the two_billion_rows example, and I noticed that the least you can scroll (ie on a single press of up/down or on a single click of the mousewheel) is 2364 rows at a time. This appears to be the behavior of any sufficiently long regular-table. This creates a UX problem, as there doesn't seem to be a way to scroll, eg, the 1000th row into view, much less a way to position the 1000th row in a specific location on my screen.

The implementation of this behavior is in the [`_calculate_row_range` function](https://github.com/jpmorganchase/regular-table/blob/2d5babaac6dd70d813f6c35d46693681aad9c78a/src/js/scroll_panel.js#L147). I think there's three questions here:

- What's the intended UX for scrolling to a specific row?
- Does it make sense for regular-table to be able to scroll several thousands rows on a single keypress/scroll wheel tic? Or should it max out at 2-3?
- Given the above UX considerations, what needs to change in the implementation (if anything)?