JetDiagnosticsTest migrated to TestGenerator

- test data files renamed from *.jet to *.kt

compiler/testData/diagnostics/tests/regressions/kt469.kt

@@ -0,0 +1,28 @@
+
+package kt469
+
+//KT-512 plusAssign() : Unit does not work properly
+import java.util.*
+
+fun bar(list : List<Int>) {
+    for (i in 1..10) {
+        list += i // error
+    }
+    System.out.println(list)
+}
+
+fun <T> List<T>.plusAssign(t : T) {
+    add(t)
+}
+
+//KT-469 Allow val-reassignment when appropriate functions are defined
+fun foo() {
+    val m = MyNumber(2)
+    m -= MyNumber(3)           //should not be error here
+}
+
+class MyNumber(var i: Int) {
+    fun minusAssign(m : MyNumber) {
+        i -= m.i
+    }
+}