Clean up alias handling.

There is no need to print a stacktrace when an alias fails, we do not do
this for normal commands. We also now give error messages when attempting
to register an alias instead of having them just silently not function.

src/main/java/org/bukkit/command/FormattedCommandAlias.java

@@ -48,7 +48,6 @@ public class FormattedCommandAlias extends Command {
                 } else {
                     sender.sendMessage(org.bukkit.ChatColor.RED + "An internal error occurred while attempting to perform this command");
                 }
-                Bukkit.getLogger().log(Level.WARNING, "Failed to parse command alias " + commandLabel + ": " + formatString, throwable);
                 return false;
             }
         }