Interactive mode: internal commands and hot keys help at the bottom of console

Internal commands and hot keys should be printed at the bottom of console when running FlubuCore in interactive mode.

Help should be displayed when interactive mode starts and should be hidden when user starts tiping. Pressing F1 or F12 should display help again until user start's typing again.

Because we won't be able to display all commands and hot keys it's still up for discussion which are going to be displayed.