Refactor all examples:

fix #575, fix #604, fix #608, fix #634, fix #712

All examples are rewritten:

* Using Best Practices
* Mostly self-contained
* New examples to complete the feature matrix
* The server-framework example is removed

example/common/root_certificates.hpp

@@ -110,6 +110,7 @@ load_root_certificates(ssl::context& ctx, boost::system::error_code& ec)
 // gratuituous template argument; thus it appears
 // like a "normal" function.
 //
+
 inline
 void
 load_root_certificates(ssl::context& ctx, boost::system::error_code& ec)
@@ -117,4 +118,14 @@ load_root_certificates(ssl::context& ctx, boost::system::error_code& ec)
     detail::load_root_certificates(ctx, ec);
 }
 
+inline
+void
+load_root_certificates(ssl::context& ctx)
+{
+    boost::system::error_code ec;
+    detail::load_root_certificates(ctx, ec);
+    if(ec)
+        throw boost::system::system_error{ec};
+}
+
 #endif