Adding bitset and complex, both untested

This makes us "feature complete (tm)" as far as things that look worth serializing in the standard library

just need the unit tests for these then we can profile size and speed vs boost

binary_archive/bitset.hpp

@@ -0,0 +1,83 @@
+#ifndef CEREAL_BINARY_ARCHIVE_BITSET_HPP_
+#define CEREAL_BINARY_ARCHIVE_BITSET_HPP_
+
+#include <cereal/binary_archive/binary_archive.hpp>
+#include <bitset>
+
+namespace cereal
+{
+  namespace bitset_detail
+  {
+    enum class type : uint8_t
+    {
+      ulong,
+      uulong,
+      string
+    };
+
+  };
+
+  //! Serializing (save) for std::bitset to binary
+  template <size_t N> inline
+  void save( BinaryOutputArchive & ar, std::bitset<N> const & bits )
+  {
+    try
+    {
+      auto const b = bits.to_ulong();
+      ar & bitset_detail::type::ulong;
+      ar & b;
+    }
+    catch( std::overflow_error const & e )
+    {
+      try
+      {
+        auto const b = bits.to_uulong();
+        ar & bitset_detail::type::uulong;
+        ar & b;
+      }
+      catch( std::overflow_error const & e )
+      {
+        ar & bitset_detail::type::string;
+        ar & bits.to_string();
+      }
+    }
+  }
+
+  //! Serializing (load) for std::bitset to binary
+  template <size_t N> inline
+  void load( BinaryInputArchive & ar, std::bitset<N> & bits )
+  {
+    bitset_detail::type t;
+    ar & t;
+
+    switch( t )
+    {
+      case bitset_detail::type::ulong:
+      {
+        unsigned long b;
+        ar & b;
+        bits = std::bitset<N>( b );
+        break;
+      }
+      case bitset_detail::type::uulong:
+      {
+        unsigned long long b;
+        ar & b;
+        bits = std::bitset<N>( b );
+        break;
+      }
+      case bitset_detail::type::string:
+      {
+        std::string b;
+        ar & b;
+        bits = std::bitset<N>( b );
+        break;
+      }
+      default:
+        throw 1;
+        // TODO: emit some kind of error
+    }
+  }
+} // namespace cereal
+
+#endif // CEREAL_BINARY_ARCHIVE_BITSET_HPP_