Deprecated the system used to register commands.

Author: Darkhax

src/main/java/net/darkhax/bookshelf/registry/CommandRegistry.java

@@ -52,8 +52,15 @@ public void initialize (IEventBus bus) {
         }
     }
 
+    /**
+     * @deprecated The static instantiation of commands seems to make some mixin mods very
+     *             unhappy. As a result this approach to registering commands has been
+     *             deprecated and will be removed in future updates.
+     */
+    @Deprecated
     public LiteralArgumentBuilder<CommandSource> registerCommand (LiteralArgumentBuilder<CommandSource> command) {
 
+        this.logger.error("Registered a command using a deprecated method. This will cause errors! {]", command);
         this.commands.add(command);
         return command;
     }
@@ -62,7 +69,7 @@ private void registerCommands (RegisterCommandsEvent event) {
 
         if (!this.commands.isEmpty()) {
 
-            this.logger.info("Registering {} commands.", this.commands.size());
+            this.logger.info("Registering {} commands. This mod is using a deprecated system!", this.commands.size());
             final CommandDispatcher<CommandSource> dispatcher = event.getDispatcher();
 
             for (final LiteralArgumentBuilder<CommandSource> command : this.commands) {