NH4: Describe map under cursor when targeting

Describe things while moving the cursor over them in getpos
Alex Smith <ais523@bham.ac.uk>
d90a5a152948686b7979085d962de3d91a856775
Remove unused flags.null

In NetHack this was how the 'null' option was reflected in the game
(default true), with the effect of calling 'tputs("$<50>", 1, xputc)' in
the TTY interface in tty_delay_output() for its 50 ms delay.  NitroHack
no longer contains the TTY interface, so this flag field is unused.