[fixes #2838] Handle anonymous classes properly

Generated qualified names (e.g. Outer.Inner) now stop at anonymous
classes instead of adding an empty part. All handlers that add static
fields/methods/types now add error messages instead of generating
invalid code.

test/transform/resource/after-ecj/WithInAnonymousClass.java

@@ -0,0 +1,23 @@
+import lombok.With;
+public class WithInAnonymousClass {
+  Object annonymous = new Object() {
+    @With class Inner {
+      private String string;
+      private Inner(String string) {
+        super();
+      }
+      /**
+       * @return a clone of this object, except with this updated property (returns {@code this} if an identical value is passed).
+       */
+      public @java.lang.SuppressWarnings("all") Inner withString(final String string) {
+        return ((this.string == string) ? this : new Inner(string));
+      }
+    }
+    x() {
+      super();
+    }
+  };
+  public WithInAnonymousClass() {
+    super();
+  }
+}