Extended prompt library functions.

Modules
		gdb os

Functions
		prompt_help() Generate help dynamically from the __doc__ strings of attribute functions. substitute_prompt(prompt) Perform substitutions on PROMPT.

Data
		prompt_substitutions = {'[': <function _prompt_noprint_begin>, r'\': <function _prompt_bs>, ']': <function _prompt_noprint_end>, 'e': <function _prompt_esc>, 'f': <function _prompt_frame>, 'n': <function _prompt_n>, 'p': <function _prompt_param>, 'r': <function _prompt_r>, 't': <function _prompt_thread>, 'v': <function _prompt_version>, ...}