Suggestion: Limit the amount of items per spider

[mmmbacon]

We are using your tool for our maps integration. It's very good, however I do not see the option to place a limit on the amount of markers per spider that can be rendered. In our case we sometimes have thousands of google map markers at the same position.

There should maybe be some control to specify the maximum amount of items to render per spider, othwerwise, opening that spider will wreak havoc on the google map.

I will probably work on a PR at some point in the near future but I just wanted to add this suggestion here.