Refactoring MainActivity to GameActivity
As in the previous projects, MainActivity is a bit vague, so let's refactor MainActivity to GameActivity.
In the project panel, right-click the MainActivity file and select Refactor | Rename. In the pop-up window, change MainActivity to GameActivity. Leave all the other options at the defaults and left-click the Refactor button.
Notice the filename in the project panel has changed as expected but also multiple occurrences of MainActivity have been changed to GameActivity in the AndroidManifest.xml file, as well as an instance in the GameActivity.java file.
Let's set the screen orientation.
