Checks for 'import android.R' statements, which are usually accidental

Importing android.R is usually not intentional; it sometimes happens when you use an IDE and ask it to automatically add imports at a time when your project's R class it not present.

Once the import is there you might get a lot of "confusing" error messages because of course the fields available on android.R are not the ones you'd expect from just looking at your own R class.