This is the way GNOME and Windows present this information, and I think it's clearer
than using a decimal value.
The underlying value is still a float, we just convert to an int in percentage form for
+1. This is also in line with typical zoom factors in other applications such as Okular, which also use percent values.
+1. I find this a bit easier on the eyes.
@romangg, are you good with this?