fix: SVG and images were inverted

This is because I called commands with (x, y) instead of (y, x)
Fixes #47

src/convert/mod.rs

@@ -22,7 +22,7 @@ use crate::Module;
 /// For the square shape, the svg is `M{x},{y}h1v1h-1`
 ///
 /// ```rust
-/// fn square(y: usize, x: usize) -> String {
+/// fn square(y: usize, x: usize, _module: Module) -> String {
 ///     format!("M{x},{y}h1v1h-1")
 /// }
 /// ```

src/convert/svg.rs

@@ -276,7 +276,7 @@ impl SvgBuilder {
                 }
 
                 for (i, command) in commands.iter().enumerate() {
-                    paths[i].push_str(&command(x + self.margin, y + self.margin, cell));
+                    paths[i].push_str(&command(y + self.margin, x + self.margin, cell));
                 }
             }
         }

src/tests/svg.rs

@@ -20,3 +20,33 @@ fn it_embeds_an_image_via_data_uri() {
     let expected_href = format!(r#"href="{data_uri}""#);
     assert!(svg.contains(&expected_href));
 }
+
+#[cfg(feature = "svg")]
+#[test]
+fn check_svg_is_not_inverted() {
+    use crate::convert::svg::SvgBuilder;
+    use crate::convert::Builder;
+    use crate::{QRBuilder, Version, ECL};
+
+    let qrcode = QRBuilder::new("Test")
+        .ecl(ECL::M)
+        .version(Version::V01)
+        .build()
+        .unwrap();
+
+    const MARGIN: usize = 4;
+    let svg = SvgBuilder::default().margin(MARGIN).to_str(&qrcode);
+
+    let size = qrcode.size;
+    for y in 0..size {
+        for x in 0..size {
+            let index = y * size + x;
+            let expected = qrcode.data[index];
+            if expected.value() {
+                dbg!((y, x));
+                let expected = format!(r#"M{x},{y}"#, x = x + MARGIN, y = y + MARGIN);
+                assert!(svg.contains(&expected));
+            }
+        }
+    }
+}