Add DataOnly plugin to support non-code plugins that just override files

Braver.Plugins/DataOnlyPlugin.cs

@@ -0,0 +1,41 @@
+// This program and the accompanying materials are made available under the terms of the
+//  Eclipse Public License v2.0 which accompanies this distribution, and is available at
+//  https://www.eclipse.org/legal/epl-v20.html
+//  
+//  SPDX-License-Identifier: EPL-2.0
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Braver.Plugins {
+    public class DataOnlyPlugin : Plugin {
+
+        private string _root;
+
+        public override string Name => $"Data Plugin: {_root}";
+        public override Version Version => new Version(1, 0, 0);
+        public override object ConfigObject => null;
+
+        public DataOnlyPlugin(string root) { 
+            _root = root;
+        }
+
+        public override IEnumerable<IPluginInstance> Get(string context, Type t) {
+            throw new NotImplementedException();
+        }
+
+        public override IEnumerable<Type> GetPluginInstances() {
+            return Enumerable.Empty<Type>();
+        }
+
+        public override void Init(BGame game) {
+            string data = Path.Combine(_root, "BraverData");
+            if (Directory.Exists(data)) {
+                foreach(string folder in Directory.GetDirectories(data)) {
+                    game.AddDataSource(Path.GetFileName(folder), new FileDataSource(folder));
+                }
+            }
+        }
+    }
+}

Braver.Plugins/Plugin.cs

@@ -93,7 +93,7 @@ namespace Braver.Plugins {
                     Plugin = pl,
                     Config = configs.Configs.FirstOrDefault(cfg => cfg.PluginClass == pl.GetType().FullName) ?? new PluginConfig(),
                 })
-                .Where(pl => pl.Config.Enabled)
+                .Where(pl => pl.Config.Enabled || (pl.Plugin is DataOnlyPlugin))
                 .OrderBy(pl => pl.Config.Priority);
 
             foreach(var p in configuredPlugins) {

Braver/FGame.cs

@@ -144,6 +144,9 @@ namespace Braver {
                             new FileDataSource(folder)
                         };
                     }
+                    if (Directory.Exists(Path.Combine(folder, "BraverData"))) {
+                        plugins.Add(new DataOnlyPlugin(folder));
+                    }
                 }
 
                 if (plugins.Any()) {