Add foreach support for TreeItem

Also, removed a few examples from the build list to save some pipeline time

.github/workflows/pipeline.yml

@@ -38,21 +38,9 @@ jobs:
           # In this mode, `mainSourceFile` is excluded and `version (unittest)` are included
           # See https://dub.pm/package-format-json.html#configurations
           dub test
-          cd examples/bezier
-          dub build -b=release
-          cd ../dminer
-          dub build -b=release
-          cd ../dmledit
-          dub build -b=release
-          cd ../dragon
-          dub build -b=release
-          cd ../example1
+          cd examples/example1
           dub build -b=release
           cd ../helloworld
           dub build -b=release
-          cd ../ircclient
-          dub build -b=release
           cd ../opengl
-          dub build -b=release
-          cd ../tetris
           dub build -b=release

.gitignore

@@ -27,3 +27,4 @@ lib/res
 *.lst
 *.a
 dlangui-test-default
+.vscode

src/dlangui/widgets/tree.d

@@ -268,6 +268,10 @@ class TreeItem {
         return this;
     }
 
+    /// Support foreach
+    int opApply(int delegate(ref TreeItem) callback) {
+        return _children.opApply(callback);
+    }
 
     /// returns true if item has at least one child
     @property bool hasChildren() { return childCount > 0; }