These changes prepare Overlay for the Universal Port and Hub and Spoke
features.
* Add [overlay configuration section:
The [overlay] section uses the new BasicConfig interface that
supports key-value pairs in the section. Some exposition is added to the
example cfg file. The new settings for overlay are related to the Hub and
Spoke feature which is currently in development. Production servers should
not set these configuration options, they are clearly marked experimental
in the example cfg file.
Other changes:
* Use _MSC_VER to detect Visual Studio
* Use ssl_bundle in Overlay::Peer
* Use shared_ptr to SSL context in Overlay:
* Removed undocumented PEER_SSL_CIPHER_LIST configuration setting
* Add Section::name: The Section object now stores its name for better diagnostic messages.
The MultiSocket is obsolete technology which is superceded by a more
straightforward, template based implementation that is compatible with
boost::asio::coroutines. This removes support for the unused PROXY handshake
feature. After this change a large number of classes and source files may be
removed.
* More fine-grained Section mutators
* Add remap for mapping legacy single sections to key value pairs
* Add output stream operators for BasicConfig and Section
* Allow section values to be overwritten from command line
* Update rpc key/value configs from command line
* Add RPC::Setup with defaults and remap legacy rpc sections
