Remove Button import in MainActivity

Author: yawnoc

app/src/main/java/io/github/yawnoc/strokeinput/MainActivity.java

@@ -14,7 +14,6 @@
 import android.provider.Settings;
 import android.view.View;
 import android.view.inputmethod.InputMethodManager;
-import android.widget.Button;
 
 /*
   The main activity of the application.