Make some changes to allow not using steamcmd for mod downloads

lib/pathtools.dart

@@ -17,6 +17,50 @@ class PathHelper {
     return this;
   }
 
+  PathHelper conditionalResolve(bool flag, String path) {
+    if (flag) pth += Platform.pathSeparator + path;
+    return this;
+  }
+
+  bool deleteDirectory({bool recursive = false}) {
+    Directory dir = new Directory(build());
+    try {
+      dir.deleteSync(recursive: recursive);
+
+      return true;
+    } catch (E) {
+      return false;
+    }
+  }
+
+  bool deleteFile() {
+    File file = new File(build());
+    try {
+      file.deleteSync(recursive: true);
+
+      return true;
+    } catch (E) {
+      return false;
+    }
+  }
+
+  PathHelper removeDir() {
+    deleteDirectory(recursive: true);
+    return this;
+  }
+
+  PathHelper removeFile() {
+    deleteFile();
+    return this;
+  }
+
+  PathHelper mkdir() {
+    Directory dir = new Directory(build());
+    dir.createSync(recursive: true);
+
+    return this;
+  }
+
   String build() {
     return pth;
   }