Hi,
at the moment gdb's "help all" command is not as helpful as it could be 
because:

1. It's not mentioned in the output of "help".
2. The output of "help all" lacks any structure -- like visual grouping by 
classes.
3. The prefix commands are printed in weird order. For example, the
"append" and "append binary" commands are printed a couple of screens apart.

This patch fixes all that, and also mentions "apropos" in the output 
of "help".

OK?

- Volodya

	* commands.h (enum command_class): Use different
	values for class_deprecated and class_run.
	* cli/cli-decode.c: (print_help_for_command): New.
	(apropos_cmd): Use the above.
	(help_list): Mention 'help all'
	and 'apropos' when printing top-level help.
	(help_all): Print the class name before printing
	commands in that class.  Don't print prefix commands
	here, instead pass recurse flag to help_cmd_list.
	Print list of unclassified commands at the end.
	(help_cmd_list): When recursing, use all_commands class.
	Recurse only if the class of the command matches.