make single-choice mode work in KeyChoiceAdapter

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/adapter/KeyChoiceAdapter.java

@@ -82,6 +82,8 @@ public class KeyChoiceAdapter extends FlexibleAdapter<KeyChoiceItem> {
             throw new IllegalStateException("Cannot get active item in single select mode!");
         }
 
+        clearSelection();
+
         Integer prevActiveItem = this.activeItem;
         this.activeItem = newActiveItem;
 
@@ -89,6 +91,7 @@ public class KeyChoiceAdapter extends FlexibleAdapter<KeyChoiceItem> {
             notifyItemChanged(prevActiveItem);
         }
         if (newActiveItem != null) {
+            toggleSelection(newActiveItem);
             notifyItemChanged(newActiveItem);
         }
     }

OpenKeychain/src/main/res/layout/api_remote_deduplicate.xml

@@ -132,7 +132,6 @@
             android:layout_height="wrap_content"
             android:text="Select"
             android:id="@+id/button_select"
-            android:enabled="false"
             style="?buttonBarButtonStyle" />
 
     </LinearLayout>

OpenKeychain/src/main/res/layout/api_remote_select_authentication_key.xml

@@ -116,7 +116,6 @@
             android:layout_height="wrap_content"
             android:text="Select"
             android:id="@+id/button_select"
-            android:enabled="false"
             style="?buttonBarButtonStyle" />
 
     </LinearLayout>