* NEWS: Document "define" for prefixed commands.

	* NEWS: Document "define" for prefixed commands.
	* cli/cli-cmds.c (show_user): Update calls to show_user_1.  Call
	show_user_1 for prefix commands.
	* cli/cli-decode.c (help_cmd_list): Recurse for "help user-defined".
	* cli/cli-script.c (validate_comname): Rewrite to handle prefix
	commands.  Return the containing command list.
	(define_command, document_command): Update to handle prefix commands.
	(show_user_1): Add prefix and name arguments.  Handle prefix
	commands.
	* cli/cli-script.h (show_user_1): Update prototype.

	doc/
	* gdb.texinfo (Define, Hooks): Document prefix command support.

	testsuite/
	* gdb.base/define.exp: Test defining and hooking prefix commands.
	* gdb.python/python.exp: Update test for "show user" output.