void setmdmdata(char bits, char parity, char stop);

is changed to:

void setmdmdata(char bits, char parity, char stop, int rings);

where:
bits == '5' ... '8'
parity == 'E' || 'O' || 'N'
stop == '1' || '2'
rings == number of 'RINGING' messages from modem on outgoing call in progress.
(read the manual)

Buffering is now disabled. We process a char at a time but you can set buffer
on again (see ChangeLog).

