Add maxResults option to Index.range

[HatulaPro]

Implementing #49

Running 10000 small bbox queries from bench.js on my machine (no maxResults provided, using default):

Before:
14.086ms
13.47ms
14.196ms
13.818ms
13.005ms

Avg: 13.715ms

After:
14.913ms
14.432ms
14.443ms
14.134ms
14.438ms

Avg: 14.472ms

• was considering passing it as an object in case we'd want more options in the future, let me know what you think

[HarelM]

@mourner, any chance you can take a look at this?

[mourner]

@HarelM sorry, I got a bit concerned about the potential performance regression from this, looking at the benchmarks, so couldn't merge it right away, but haven't had a chance to dig deeper yet.

[HarelM]

Do let us know if there's anything we can do in order push this forward.
Another approach would be to create a new "API entry point" to facilitate this need and thus avoiding degradation in the current API.
But this might mean duplicating some of the code, which I'm not sure is a good idea.
But we'd love to know what you think should be the right solution and we'll be happy to move it forward.