Drag'n'drop zooms out to infinity (and beyond?)

[mbredif]

Steps to Reproduce

1. download https://donneespubliques.meteofrance.fr/donnees_libres/Txt/Synop/postesSynop.json
2. rename it as postesSynop.geojson (necessary as json is not a registered extension in this example Drag'N'drop improvements #1166 )
3. drag n drop it into http://www.itowns-project.org/itowns/examples/drag-n-drop.html

Expected Behavior

see the content (points) of this geojson on the itowns globe

Actual Behavior

the viewer zooms out very far and the globe is no longer visible

Possible Cause/Fix/Solution

The extent of this geojson is quite large, so that it may not be possible to see all points at once

[zarov]

This is due to this line, because the dimensions of the extent of this file is quite big, resulting in a range value approximately equals to 23634000000. To fix it, the linked formula needs more tweaking, that I didn't take time to do when I wrote this.

[mgermerie]

The DragNDrop plugin should be updated to use new CameraUtils method.