Disable wizard mode when the done slide of the intro is reached

This fixes a number of issues that can happen when navigating back to previous
slides, by disabling back navigation entirely. One such issue is that when
navigating back from the last slide, one would always land on the
password/biometrics setup slide, even if "none" was selected on the security
picker slide.

app/src/main/java/com/beemdevelopment/aegis/ui/IntroActivity.java

@@ -83,6 +83,10 @@ public class IntroActivity extends AppIntro2 {
             }
         }
 
+        if (newFragment == _endSlide) {
+            setWizardMode(false);
+        }
+
         setSwipeLock(true);
     }