Adds asio library and Storage Module

lib/asio-1.18.0/doc/asio/overview/cpp2011/move_handlers.html

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+<div class="titlepage"><div><div><h4 class="title">
+<a name="asio.overview.cpp2011.move_handlers"></a><a class="link" href="move_handlers.html" title="Movable Handlers">Movable Handlers</a>
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+<p>
+          With C++11 and later, user-defined completion handlers are only required
+          to be move constructible, and are not required to be copy constructible.
+        </p>
+<p>
+          When move support is enabled, asynchronous that are documented as follows:
+        </p>
+<pre class="programlisting">template &lt;typename Handler&gt;
+void async_XYZ(..., Handler handler);
+</pre>
+<p>
+          are actually declared as:
+        </p>
+<pre class="programlisting">template &lt;typename Handler&gt;
+void async_XYZ(..., Handler&amp;&amp; handler);
+</pre>
+<p>
+          The handler argument is perfectly forwarded and the move construction occurs
+          within the body of <code class="computeroutput">async_XYZ()</code>. This ensures that all other
+          function arguments are evaluated prior to the move. This is critical when
+          the other arguments to <code class="computeroutput">async_XYZ()</code> are members of the handler.
+          For example:
+        </p>
+<pre class="programlisting">struct my_operation
+{
+  unique_ptr&lt;tcp::socket&gt; socket;
+  unique_ptr&lt;vector&lt;char&gt;&gt; buffer;
+  ...
+  void operator(error_code ec, size_t length)
+  {
+    ...
+    socket-&gt;async_read_some(asio::buffer(*buffer), std::move(*this));
+    ...
+  }
+};
+</pre>
+<p>
+          Move support is automatically enabled for <code class="literal">g++</code> 4.5 and
+          later, when the <code class="literal">-std=c++0x</code> or <code class="literal">-std=gnu++0x</code>
+          compiler options are used. It may be disabled by defining <code class="computeroutput">ASIO_DISABLE_MOVE</code>,
+          or explicitly enabled for other compilers by defining <code class="computeroutput">ASIO_HAS_MOVE</code>.
+          Note that these macros also affect the availability of <a class="link" href="move_objects.html" title="Movable I/O Objects">movable
+          I/O objects</a>.
+        </p>
+</div>
+<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
+<td align="left"></td>
+<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M.
+      Kohlhoff<p>
+        Distributed under the Boost Software License, Version 1.0. (See accompanying
+        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
+      </p>
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