Manually implement Clone and Debug for Buffer

fix #10

sailfish/src/runtime/buffer.rs

@@ -10,7 +10,6 @@ const MEMORY_LAYOUT: Layout = unsafe { Layout::from_size_align_unchecked(1, 1) }
 ///
 /// This struct is quite simular to `String`, but some methods are
 /// re-implemented for faster buffering.
-#[derive(Clone, Debug)]
 pub struct Buffer {
     data: *mut u8,
     len: usize,
@@ -136,6 +135,23 @@ impl Buffer {
     }
 }
 
+impl Clone for Buffer {
+    fn clone(&self) -> Self {
+        let layout = unsafe { alloc(Layout::from_size_align_unchecked(self.len, 1)) };
+        Self {
+            data: layout,
+            len: self.len,
+            capacity: self.len,
+        }
+    }
+}
+
+impl fmt::Debug for Buffer {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.as_str().fmt(f)
+    }
+}
+
 impl Drop for Buffer {
     fn drop(&mut self) {
         if !self.data.is_null() {