Revert rust-ndarray#1567 to prepare for a patch release.

This reverts commit 953f2e9.
The commit will now live on the `refactor` branch until
more of the new layout code is ready

Author: akern40

src/layout/bitset.rs

@@ -0,0 +1,32 @@
+// Copyright 2017 bluss and ndarray developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use super::LayoutBitset;
+
+const LAYOUT_NAMES: &[&str] = &["C", "F", "c", "f"];
+
+use std::fmt;
+
+impl fmt::Debug for LayoutBitset
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    {
+        if self.0 == 0 {
+            write!(f, "Custom")?
+        } else {
+            (0..32).filter(|&i| self.is(1 << i)).try_fold((), |_, i| {
+                if let Some(name) = LAYOUT_NAMES.get(i) {
+                    write!(f, "{}", name)
+                } else {
+                    write!(f, "{:#x}", i)
+                }
+            })?;
+        };
+        write!(f, " ({:#x})", self.0)
+    }
+}