add a shortcut to navigate through images...

[sozap]

Hi,
By pressing the left/right arrow key we would navigate between each images in fullscreen, just like if we selected one image after the other and pressed the 2 shortcut.
This allows to use BeeRef a bit like a standard image viewer and navigate through all images in the scene.

What the order of image would be: it's probably safe to pick the order in which they were added to the scene.
Obviously this function isn't always helpful and it really depends on your workflow, but sometime we might just want to quickly scan through every image until we find what we need !

Thanks a lot ! beeref is pretty cool, I'll try to use it more and more from now on !