Improved mod interface; Basic mod install process

ZuneModCore/Mod.cs

@@ -29,15 +29,29 @@ namespace ZuneModCore
 
         public virtual Task Init() => Task.CompletedTask;
 
-        public abstract Task<bool> Apply();
+        public abstract Task<string?> Apply();
 
-        public abstract Task<bool> Reset();
+        public abstract Task<string?> Reset();
 
         public abstract AbstractUIElementGroup? OptionsUI { get; }
 
-        public string StorageDirectory => Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
-            "ZuneModCore", Id);
+        public string StorageDirectory
+        {
+            get
+            {
+                string dir = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "ZuneModCore", Id);
+                // Create the directory just in case the consumer assumes the folder exists already
+                Directory.CreateDirectory(dir);
+                return dir;
+            }
+        }
 
         public abstract IReadOnlyList<Type>? DependentMods { get; }
+
+        internal FileStream OpenFileInStorageDirectory(string filename)
+        {
+            FileInfo info = new(Path.Combine(StorageDirectory, filename));
+            return File.Create(info.FullName);
+        }
     }
 }