width/height attributes often not removed with --enable-viewboxing due to rounding errors

[Ede123]

The function properlySizeDoc is supposed to set a viewBox with the images dimensions and remove width/height attributes.

The problem is that we preserve width/height if a viewBox is already present and the values of both do not match perfectly.

Due to rounding in Scour they will almost never match for non-integer dimensions.

[Ede123]

Easiest solutions will probably be to apply rounding to the viewBox attribute, too. This will not only prevent rounding errors in Scour from causing problems but will also resolve rounding errors by other applications.