Add 'engine/' from commit 'a8e37fc010'

git-subtree-dir: engine
git-subtree-mainline: b74841629e
git-subtree-split: a8e37fc010

engine/modules/gdscript/tests/scripts/parser/warnings/unused_variable.gd

@@ -0,0 +1,4 @@
+func test():
+	var unused = "not used"
+
+	var _unused = "not used, but no warning since the variable name starts with an underscore"