Unordered: Reorganization to use void pointers and other things.

Helps allocators which can't use incomplete pointers, and avoid using
base pointers where that might not be possible.  And some other
reorganization. Storing arguments to emplace in a structure when
variadic template parameters aren't available. Changed some of the odd
design for working with older compilers.

[SVN r74742]

test/unordered/compile_set.cpp

@@ -128,7 +128,7 @@ UNORDERED_AUTO_TEST(test1)
     std::equal_to<int> equal_to;
     int value = 0;
 
-    std::cout<<"Test unordered_set.\n";
+    std::cout<<"Test unordered_set." << std::endl;
 
     boost::unordered_set<int> set;
     
@@ -145,7 +145,7 @@ UNORDERED_AUTO_TEST(test1)
     unordered_set_test(set2, value);
     unordered_copyable_test(set2, value, value, hash, equal_to);
 
-    std::cout<<"Test unordered_multiset.\n";
+    std::cout<<"Test unordered_multiset." << std::endl;
 
     boost::unordered_multiset<int> multiset;