[feature] low res pixel blur

[a-viv-a]

At the moment there is only a smooth blur—a lot of data can be retrieved from smooth blurs, like text and decent approximations of images. The default blur seems pretty heavy, so maybe this is unneeded, but I think it would be really helpful to have a pixel blur which can be applied as a distinct option from the existing smooth (Gaussian?) blur, for censoring names ect.

Spectacle is an example of a screenshot tool that I know has both blur types.

Thanks for an awesome tool!