Add PiP browser mode

Now you can view the video in a small and draggable video window. The script will remember the location of that window, so next video will show up in the same location.
It seems easy but it takes me 2 days to do it. A lot of things and bugs to fix.

Better browser and browserfull handling

Now I recommend using browserfull mode with Oculus Browser to browse your VR videos in Stash.
Viewing each video can save a few clicks.

All browser mode works for now.

v0.3

Update README.md