Tips and option to disable them

Adds a more general way to handle gameplay tips, and adds
a boolean option "tips", which can be used to disable all
tips.  Adds a helpful longer message when the game goes
into the "farlook" mode.

Also adds a lua binding to easily show multi-line text
in a menu window.

Breaks save compat.

include/extern.h

@@ -966,6 +966,7 @@ extern int wiz_debug_cmd_traveldisplay(void);
 extern boolean u_rooted(void);
 extern boolean u_maybe_impaired(void);
 extern const char *u_locomotion(const char *);
+extern void handle_tip(int);
 extern void domove(void);
 extern void runmode_delay_output(void);
 extern void overexert_hp(void);