Number of pages loaded initially is 2X MAX_PAGE_LOAD_RANGE

Hi,

Number of pages loaded when I'm in 1st page is 2X MAX_PAGE_LOAD_RANGE. Which is quiet heavy.

Is there any way to configure MAX_PAGE_LOAD_RANGE. (Without changing source)

This is the current configurations that I'm using.

```
viewer = Crocodoc.createViewer('.viewer', {
url: "./InTimeOktoober14/assets",
layout: Crocodoc.LAYOUT_VERTICAL_SINGLE_COLUMN,
enableTextSelection: true,
enableDragging: false,
useWindowAsViewport: true
});
viewer.on('pagefocus', function (event) {
console.log(event.data.page);
});

// This is how I got to know number of pages loaded.
viewer.on('pageload', function (event) {
console.log("loaded", event.data.page);
});
viewer.on('pageunload', function (event) {
console.log("unloaded", event.data.page);
});
viewer.load();
```

Please suggest, thanks in advance.

Start with the viewer configuration in the issue and trace how MAX_PAGE_LOAD_RANGE controls the initial page loading and pageunload behavior. Determine whether that setting has a supported configuration entry point, then verify the result using the reported pageload and pageunload events; done means the initial load range can be controlled without changing source, or the limitation is documented.

Written by the indexing model from the issue text.