Link libdcf77.so instead of clients against libm as it uses exp2() in input.c
Remove extraneous blank lines.
Factor out presentation-related code from input.[ch] :
 - Move display_bit_file() to dcf77pi-analyze.c and adjust prototype
- Move presentation-related code from next_bit() to dcf77pi[-analyze].c and remove now unneeded parameter
- Move display_bit_gui(), draw_input_window(), and switch_logfile() to dcf77pi.c and adjust prototype
- Pass bit-related information from get_bit_live() to dcf77pi.c in a new structure bitinfo, declared in input.h
- Move declaration of input_win to dcf77pi.c
- Remove dependency on guifuncs and ncurses for input.[ch]
- Add new helper function close_logfile() to input.[ch]