Add option to clamp the image to the screen

[Frost-Phoenix]

Hi,

I really like woomer and thought of a new option: clamp the image to the screen edges. For example, when moving the zoomed image, the lower-left corner would stay aligned with the lower-left corner of the screen.

Not sure if this is something you'd want to add, but I think some people (me included) might find it useful.

[coffeeispower]

The reason it doesn't clamp to the screen edges is because of the original boomer because it also allows you to do the same and the reason is that you might want to zoom into something at the corner of the screen and have that thing on the middle which you can't do if you clamp the borders.
I wouldn't mind it being a parameter but the problem is how that would work with multiple monitors