add SIGINT for KeyboardInterrupt exceptions
peanuts: fix spaces
browser thumbnails: add loading display
fix imageProvider

* use specific internalMemoryCache to avoid using the same cache across
multiple threads (need to update TuttleOFX)
* change thumbnails size to 256
* choose the time to render (middle frame if the frame exists)
* test multiple readers if there is an error
* return an empty image if we can't load the image