Refactor beast core, http, tests, and examples:

* Fix warnings
* Port cmake scripts to linux
* Add command line options for running test suites
* Add examples to CMakeLists
* Return std::uint64_t from writer::content_length
* basic_parser::write takes asio::const_buffer instead of pointer and size
* Turn message test back on now that it passes
* Rename to http::headers, use std::allocator, remove http_headers
* http::message::method is now a string
* Refactor to_string for ConstBufferSequence
* Remove chunk_encode from the public interface
* Initialize members for default constructed iterators
* Disallow default construction for dependent buffer sequences

Refactor http::message serialization:

* Serialization no longer creates a copy of the
  headers and modifies them
* New function prepare(), sets Connection, Transfer-Encoding,
  Content-Length based on the body attributes and caller options.
  Callers can use prepare() to have the fields set automatically,
  or they can set the fields manually.
* Use write for operator<<
* Tests for serialization

doc/beast.dox

@@ -108,7 +108,6 @@ INPUT = \
         ../include/beast/bind_handler.hpp \
         ../include/beast/buffer_cat.hpp \
         ../include/beast/buffers_adapter.hpp \
-        ../include/beast/buffers_debug.hpp \
         ../include/beast/consuming_buffers.hpp \
         ../include/beast/handler_alloc.hpp \
         ../include/beast/http.hpp \
@@ -117,6 +116,7 @@ INPUT = \
         ../include/beast/static_streambuf.hpp \
         ../include/beast/streambuf.hpp \
         ../include/beast/streambuf_readstream.hpp \
+        ../include/beast/to_string.hpp \
         ../include/beast/type_check.hpp \
         ../include/beast/websocket.hpp \
         ../include/beast/write_streambuf.hpp \

doc/beast.qbk

@@ -115,9 +115,10 @@ int main()
     using namespace beast::http;
 
     // Send HTTP request using beast
-    request<empty_body> req({method_t::http_get, "/", 11});
+    request<empty_body> req({"GET", "/", 11});
     req.headers.replace("Host", host + ":" + std::to_string(sock.remote_endpoint().port()));
     req.headers.replace("User-Agent", "Beast");
+    prepare(req);
     write(sock, req);
 
     // Receive and print HTTP response using beast
@@ -130,8 +131,8 @@ int main()
 
 Establish a WebSocket connection, send a message and receive the reply:
 ```
+#include <beast/to_string.hpp>
 #include <beast/websocket.hpp>
-#include <beast/buffers_debug.hpp>
 #include <boost/asio.hpp>
 #include <iostream>
 #include <string>
@@ -158,8 +159,7 @@ int main()
     opcode op;
     ws.read(op, sb);
     ws.close(close_code::normal);
-    std::cout <<
-        beast::debug::buffers_to_string(sb.data()) << "\n";
+    std::cout << to_string(sb.data()) << "\n";
 }
 ```
 

doc/quickref.xml

@@ -34,6 +34,7 @@
             <member><link linkend="beast.ref.http__basic_streambuf_body">basic_streambuf_body</link></member>
             <member><link linkend="beast.ref.http__empty_body">empty_body</link></member>
             <member><link linkend="beast.ref.http__error_code">error_code</link></member>
+            <member><link linkend="beast.ref.http__headers">headers</link></member>
             <member><link linkend="beast.ref.http__message">message</link></member>
             <member><link linkend="beast.ref.http__resume_context">resume_context</link></member>
             <member><link linkend="beast.ref.http__streambuf_body">streambuf_body</link></member>
@@ -49,8 +50,6 @@
           <simplelist type="vert" columns="1">
             <member><link linkend="beast.ref.http__async_read">async_read</link></member>
             <member><link linkend="beast.ref.http__async_write">async_write</link></member>
-            <member><link linkend="beast.ref.http__chunk_encode">chunk_encode</link></member>
-            <member><link linkend="beast.ref.http__chunk_encode_final">chunk_encode_final</link></member>
             <member><link linkend="beast.ref.http__read">read</link></member>
             <member><link linkend="beast.ref.http__write">write</link></member>
           </simplelist>

doc/types.qbk

@@ -252,7 +252,7 @@ In this table:
 ]
 [
     [`a.content_length()`]
-    [`std::size_t`]
+    [`std::uint64_t`]
     [
         If this member is present, it is called after initialization
         and before calls to provide buffers. The serialized message will