Add DebugFlags helper, improve format of HEADERS and SETTINGS frames

src/frame/data.rs

@@ -225,16 +225,9 @@ impl From<DataFlags> for u8 {
 
 impl fmt::Debug for DataFlags {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        let mut f = fmt.debug_struct("DataFlags");
-
-        if self.is_end_stream() {
-            f.field("end_stream", &true);
-        }
-
-        if self.is_padded() {
-            f.field("padded", &true);
-        }
-
-        f.finish()
+        util::debug_flags(fmt, self.0)
+            .flag_if(self.is_end_stream(), "END_STREAM")
+            .flag_if(self.is_padded(), "PADDED")
+            .finish()
     }
 }