src/server: usage/help/doc updates

Make "usage" messages use the same EBNF as the User's Guide;
no angle brackets.  Improve and correct various helptexts.

Specifically for the port commands, clarify that the number
is optional, and omitting it causes the current number to be
displayed.

Don't use "&function"; a function's name is its address.
Remove a couple instances of pointless whitespace; shrink a
few overlong lines.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

src/server/tcl_server.c

@@ -181,11 +181,12 @@ COMMAND_HANDLER(handle_tcl_port_command)
 static const struct command_registration tcl_command_handlers[] = {
 	{
 		.name = "tcl_port",
-		.handler = &handle_tcl_port_command,
+		.handler = handle_tcl_port_command,
 		.mode = COMMAND_CONFIG,
-		.help = "port on which to listen "
-			"for incoming TCL syntax",
-		.usage = "<port>",
+		.help = "Specify port on which to listen "
+			"for incoming Tcl syntax.  "
+			"No arguments reports Tcl port; zero disables.",
+		.usage = "[port_num]",
 	},
 	COMMAND_REGISTRATION_DONE
 };