5.2.0: new "interpolation" feature for cropped panorama

[mistic100]

The new equirectangular adapter option interpolateBackground allows to fill the gaps of cropped panoramas with blurry content, more apealing that the standard backgroundColor (formerly canvasBackground). Check the demo. The feature is currently off by default but will be on in a future version.

Note: the interpolation is asynchronous so the the panorama is first shown with only the background color applied.