API: Remove deprecated ArrayView::into_slice (use to_slice)

This could really use either name - `into_slice` for the "into" semantic
of preserving the lifetime parameter, or the `to_slice` name which is
customary for `&self` methods.

Both names have the problem that they compete with
`ArrayBase::as_slice()`, but the doc has been improved to explain some
of that.

Author: bluss

src/impl_views/conversions.rs

@@ -31,18 +31,9 @@ where
 
     /// Return the array’s data as a slice, if it is contiguous and in standard order.
     /// Return `None` otherwise.
-    #[deprecated(note = "`into_slice` has been renamed to `to_slice`", since = "0.13.0")]
-    #[allow(clippy::wrong_self_convention)]
-    pub fn into_slice(&self) -> Option<&'a [A]> {
-        if self.is_standard_layout() {
-            unsafe { Some(slice::from_raw_parts(self.ptr.as_ptr(), self.len())) }
-        } else {
-            None
-        }
-    }
-
-    /// Return the array’s data as a slice, if it is contiguous and in standard order.
-    /// Return `None` otherwise.
+    ///
+    /// Note that while the method is similar to [`ArrayBase::as_slice()`], this method tranfers
+    /// the view's lifetime to the slice, so it is a bit more powerful.
     pub fn to_slice(&self) -> Option<&'a [A]> {
         if self.is_standard_layout() {
             unsafe { Some(slice::from_raw_parts(self.ptr.as_ptr(), self.len())) }
@@ -120,6 +111,9 @@ where
 {
     /// Return the array’s data as a slice, if it is contiguous and in standard order.
     /// Return `None` otherwise.
+    ///
+    /// Note that while this is similar to [`ArrayBase::as_slice_mut()`], this method tranfers the
+    /// view's lifetime to the slice.
     pub fn into_slice(self) -> Option<&'a mut [A]> {
         self.into_slice_().ok()
     }