Refactor presentation-related code from decode_alarm.[ch]:
- Move display_alarm_file() and display_alarm_error_file() to dcf77pi-analyze.c
- Move show_civbuf_gui(), display_alarm_gui(), display_alarm_error_gui(),
  clear_alarm_gui() and draw_alarm_gui() to dcf77pi.c
- Move declaration of alarm_win from decode_alarm.h to dcf77pi.c

- Explicitly include stdio.h in dcf77pi-analyze.c
- Prune includes from decode_alarm.[ch]
readpin.c: Explicitly include stdio.h and sort includes.
Makefile: no longer link dcf77pi-analyze and readpin against guifuncs.o and libncurses,
only dcf77pi uses those objects now.