agn[?] title body Add a node to the current graph

| Examples: 
    | agn title1 body1 Add a node with title "title1" and body "body1"
    | agn "title with space" "body with space" Add a node with spaces in the title and in the body
    | agn title1 base64:Ym9keTE= Add a node with the body specified as base64
    | agn- title1 Remove a node with title "title1"
    | agn? Show this help