Only preview image files and less than 20mb

[kOld]

Only preview image files and less than 20mb, otherwise the browser will be very slow or crash completely.

For example try to preview this wikipedia image: Georgetown_PowerPlant_interior_pano.jpg

Or select a zip file with 1gb, the browser will crash after trying to read it

[JeremyFagis]

👍 Worked on it here #35, it will be available soon.