Add filename and subdirectory overrides to Config class annotation

src/main/java/com/gtnewhorizon/gtnhlib/config/Config.java

@@ -21,6 +21,17 @@
      */
     String category() default "general";
 
+    /**
+     * The subdirectory of the config directory to use. Defaults to none (config/). If you want to use a subdirectory,
+     * you must specify it as a relative path (e.g. "myMod").
+     */
+    String configSubDirectory();
+
+    /**
+     * The name of the configuration file. Defaults to the modid. The file extension (.cfg) is added automatically.
+     */
+    String filename();
+
     @Retention(RetentionPolicy.RUNTIME)
     @Target({ ElementType.FIELD, ElementType.TYPE })
     @interface LangKey {

src/main/java/com/gtnewhorizon/gtnhlib/config/ConfigurationManager.java

@@ -61,7 +61,17 @@ public static void registerConfig(Class<?> configClass) throws ConfigException {
         val category = Optional.of(cfg.category().trim()).map((cat) -> cat.length() == 0 ? null : cat).orElseThrow(
                 () -> new ConfigException("Config class " + configClass.getName() + " has an empty category!"));
         val rawConfig = configs.computeIfAbsent(cfg.modid(), (ignored) -> {
-            val c = new Configuration(configDir.resolve(cfg.modid() + ".cfg").toFile());
+            Path newConfigDir = configDir;
+            if (cfg.configSubDirectory() != null) {
+                newConfigDir = newConfigDir.resolve(cfg.configSubDirectory());
+            }
+            String fileName;
+            if (cfg.fileName() != null) {
+                fileName = cfg.fileName();
+            } else {
+                fileName = cfg.modid();
+            }
+            val c = new Configuration(newConfigDir.resolve(fileName + ".cfg").toFile());
             c.load();
             return c;
         });