This structure describes common properties of a CLI session. A CLI session is the interaction of an end user to the CLI application via a specific renderer, where the renderer can be console, telnet, web, or a GUI app for mobile. A session is created by its renderer, and it's creation procedures vary among renderer (for example, a telnet session is created when the end user connects to the application, while a console session is always instantiated once the program is run).
Forward declaration for pj_cli_sess, which will be declared in cli_imp.h.