Proposal:

• implement in C core, so all bindings that use the C lib have access to a single impl
• Provide no-argument C++ connect() and C pn_connection_open_default() to load from file named by PN_CONNECTION_CONFIG env. var. or a default place ($HOME/.pn_connection_config?)
• provide C API pn_connection_config_file(filename) and pn_connection_config_string(config_string) to apply config to a connection
• provide C++ connection_options::config_file() and config_string() to merge file or string config with other connection options