j2k: flatten test cases and testData directory structure

Move j2k/test/tests -> j2k/tests, j2k/test/testData -> j2k/testData

j2k/testData/fileOrElement/comments/comments.kt.todo

@@ -0,0 +1,25 @@
+package foo // we use package 'foo'
+
+// imports:
+import java.util.ArrayList  // we need ArrayList
+
+// let's declare a class:
+class A /* just a sample name*/() : Runnable /* let's implement Runnable */ {
+    fun foo /* again a sample name */( p: Int /* parameter p */, c: Char /* parameter c */) {
+        // let's print something:
+        System.out.println("1") // print 1
+        System.out.println("2") // print 2
+
+        System.out.println("3") // print 3
+
+        // end of printing
+
+        if (p > 0) { // do this only when p > 0
+            // we print 4 and return
+            System.out.println("3")
+            return // do not continue
+        }
+
+        // some code to be added
+    }
+} // end of class A