compilation cache: tests now part of test suite

tests/rodfiles/hallo2.nim

@@ -0,0 +1,17 @@
+discard """
+  output: "Hello World"
+"""
+
+# Test incremental type information
+
+type
+  TNode = object {.pure.}
+    le, ri: ref TNode
+    data: string
+
+proc newNode(data: string): ref TNode =
+  new(result)
+  result.data = data
+  
+echo newNode("Hello World").data
+