make syntax errors respond with 'usage'

The 'help' text will become more verbose, so its entire text will be
far more than desired when you only borked your syntax.  The usage
still allows the commands to be looked up for more help.

src/helper/startup.tcl

@@ -25,7 +25,7 @@ proc ocd_bouncer {name args} {
 			set errmsg "Command handler execution failed"
 		}
 	} else {if {$type == "group"} {
-		catch {eval ocd_help $name $args}
+		catch {eval ocd_usage $name $args}
 		set errmsg [format "%s: command requires more arguments" \
 			[concat $name " " $args]]
 	} else {