Parser concept, fixes:

A new concept Parser is introduced with routines to read from a stream
into the parser. This solves a problem with the old read interface where
messages must be default constructible and move assignable.

Parser fixes:

* Fix detect invalid reason-phrase octets
* Fix write_eof to set the 'complete' state on success
* Fix consider parse complete if eof received on empty body

WebSocket:

* Increase coverage

test/http/streambuf_body.cpp

@@ -7,3 +7,38 @@
 
 // Test that header file is self-contained.
 #include <beast/http/streambuf_body.hpp>
+
+#include <beast/core/to_string.hpp>
+#include <beast/http/headers.hpp>
+#include <beast/http/parser_v1.hpp>
+#include <beast/http/read.hpp>
+#include <beast/test/string_stream.hpp>
+#include <beast/unit_test/suite.hpp>
+
+namespace beast {
+namespace http {
+
+class streambuf_body_test : public beast::unit_test::suite
+{
+    boost::asio::io_service ios_;
+
+public:
+    void run() override
+    {
+        test::string_stream ss(ios_,
+            "HTTP/1.1 200 OK\r\n"
+            "Server: test\r\n"
+            "Content-Length: 3\r\n"
+            "\r\n"
+            "xyz");
+        parser_v1<false, streambuf_body, headers> p;
+        streambuf sb;
+        parse(ss, sb, p);
+        expect(to_string(p.get().body.data()) == "xyz");
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(streambuf_body,http,beast);
+
+} // http
+} // beast