New header-only basic_parser:

The basic_parser is rewritten to be header-only. The nodejs parser is
removed from the include subtree and placed into the test directory.
Other changes:

* Parser specific error codes in parse_error.hpp
* Add parser-bench performance testing, nodejs vs beast
* New random message generator for fuzz tests
* Test for header-only parser using random message generator
* Augmented some existing message tests to check more cases

test/http/parse_error.cpp

@@ -0,0 +1,9 @@
+//
+// Copyright (c) 2013-2016 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Test that header file is self-contained.
+#include <beast/http/parse_error.hpp>