Utility Functions
-----------------

 - Function: int rl_read_key ()
     Return the next character available.  This handles input inserted
     into the input stream via PENDING INPUT (*note Readline
     Variables::.) and `rl_stuff_char ()', macros, and characters read
     from the keyboard.

 - Function: int rl_getc (FILE *)
     Return the next character available from the keyboard.

 - Function: int rl_stuff_char (int c)
     Insert C into the Readline input stream.  It will be "read" before
     Readline attempts to read characters from the terminal with
     `rl_read_key ()'.

 - Function: int rl_initialize ()
     Initialize or re-initialize Readline's internal state.

 - Function: int rl_reset_terminal (char *terminal_name)
     Reinitialize Readline's idea of the terminal settings using
     TERMINAL_NAME as the terminal type (e.g., `vt100').

 - Function: int alphabetic (int c)
     Return 1 if C is an alphabetic character.

 - Function: int numeric (int c)
     Return 1 if C is a numeric character.

 - Function: int ding ()
     Ring the terminal bell, obeying the setting of `bell-style'.

   The following are implemented as macros, defined in `chartypes.h'.

 - Function: int uppercase_p (int c)
     Return 1 if C is an uppercase alphabetic character.

 - Function: int lowercase_p (int c)
     Return 1 if C is a lowercase alphabetic character.

 - Function: int digit_p (int c)
     Return 1 if C is a numeric character.

 - Function: int to_upper (int c)
     If C is a lowercase alphabetic character, return the corresponding
     uppercase character.

 - Function: int to_lower (int c)
     If C is an uppercase alphabetic character, return the corresponding
     lowercase character.

 - Function: int digit_value (int c)
     If C is a number, return the value it represents.