Input manager game.cpp

This applies astyle to `game::list_factions` and `game::msg_buffer`.

Than it uses the input context there, and in `game::list_missions`.

Finally it removes one input system because it's not used anymore:

- `InputEvent get_input(int ch ? '\0')`
- the enumeration `InputEvent`
- `void get_direction(int &x, int &y, InputEvent &input);`

The only remaining non-configurable input function is `long input(long ch = -1);`.