Use ButterKnife's @OnClick annotation
Add two-pane activity layout
Trying to change orientation but getting error:

IllegalArgumentException: No view found for id 0x7f07003c (com.github.dddpaul.netcat:id/pager) for fragment ResultFragment

The reason is that retained ResultFragment stores reference to ViewPager in mContainer field.
Incapsulate NetCat object in headless fragment, see
https://android.googlesource.com/platform/development/+/master/samples/ApiDemos/src/com/example/android/apis/app/FragmentRetainInstance.java
Use event to signal when NetCat object is injected and ready
Typofix
First, it looks like creating headless fragment from activity is more proper than creating from UI fragment.
In the latter case robolectric tests of this UI fragment will fail (see FragmentTestUtil).
Tests will fail with recursive transaction exception.

Second, despite of all manuals, references and SO discussions we need view id for headless fragment.
Otherwise application throws "IllegalStateException: Fragment xxx did not create a view" on Activity.setContentView.

These are necessary preconditions for this exception:
- fragment transaction in Activity.onCreate;
- fragment element in activity layout.
Merge branch 'feature/task_3' into dev