print: Adjust 100% to SVG physical dimensions

Some SVGs store there size in cm or inch. With this change, the 100% in
the print dialog is calculated according to that physical size.

Closes #141

src/decoder/formats/mod.rs

@@ -25,7 +25,7 @@ use super::{DecoderUpdate, UpdateSender};
 
 #[derive(Clone, Debug, Default)]
 pub enum ImageDimensionDetails {
-    Svg(String),
+    Svg(String, Option<(f64, f64)>),
     #[default]
     None,
 }