Remove io_impl empty file

Signed-off-by: Omar Shrit <omar@shrit.me>

src/mlpack/core/util/CMakeLists.txt

@@ -9,7 +9,6 @@ set(SOURCES
   binding_details.hpp
   io.hpp
   io.cpp
-  io_impl.hpp
   deprecated.hpp
   hyphenate_string.hpp
   is_std_vector.hpp

src/mlpack/core/util/io.hpp

@@ -307,7 +307,4 @@ class IO
 
 } // namespace mlpack
 
-// Include the actual definitions of templated methods
-#include "io_impl.hpp"
-
 #endif

src/mlpack/core/util/io_impl.hpp

@@ -1,23 +0,0 @@
-/**
- * @file core/util/io_impl.hpp
- * @author Matthew Amidon
- *
- * Implementation of templated functions of the IO class.
- *
- * mlpack is free software; you may redistribute it and/or modify it under the
- * terms of the 3-clause BSD license.  You should have received a copy of the
- * 3-clause BSD license along with mlpack.  If not, see
- * http://www.opensource.org/licenses/BSD-3-Clause for more information.
- */
-#ifndef MLPACK_CORE_UTIL_IO_IMPL_HPP
-#define MLPACK_CORE_UTIL_IO_IMPL_HPP
-
-// In case it has not already been included.
-#include "io.hpp"
-#include "prefixedoutstream.hpp"
-
-namespace mlpack {
-
-} // namespace mlpack
-
-#endif