crmode()
Class Public methods
Put the terminal into cbreak mode.
Normally, the tty driver buffers typed characters until a newline or
carriage return is typed. The ::cbreak routine disables line
buffering and erase/kill character-processing (interrupt and flow control
characters are unaffected), making characters typed by the user immediately
available to the program.
The ::nocbreak routine returns
the terminal to normal (cooked) mode.
Initially the terminal may or may not be in cb