Merge branch 'valid-xml' into 'master'

Make the Debug trait output valid XML

See merge request !1

src/element.rs

@@ -31,15 +31,17 @@ pub struct Element {
 
 impl fmt::Debug for Element {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        if let Some(ref ns) = self.namespace {
-            write!(fmt, "<{{{}}}{}", ns, self.name)?;
-        }
-        else {
         write!(fmt, "<{}", self.name)?;
+        if let Some(ref ns) = self.namespace {
+            write!(fmt, " xmlns=\"{}\"", ns)?;
         }
         for attr in &self.attributes {
             write!(fmt, " {}", attr)?;
         }
+        if self.children.is_empty() {
+            write!(fmt, "/>")?;
+        }
+        else {
             write!(fmt, ">")?;
             for child in &self.children {
                 match *child {
@@ -52,6 +54,7 @@ impl fmt::Debug for Element {
                 }
             }
             write!(fmt, "</{}>", self.name)?;
+        }
         Ok(())
     }
 }