Fixed|UI|Home: Game profiles listed in duplicate after launching

On the first launch, game profiles are populated based on the
available games, and it was possible that this operation was done
twice if the games are immediately playable.

IssueID #2203

doomsday/apps/client/src/ui/home/gamecolumnwidget.cpp

@@ -145,7 +145,6 @@ DENG_GUI_PIMPL(GameColumnWidget)
                 .setInput(Rule::Top,   menu->rule().bottom());
 
         DoomsdayApp::games().audienceForReadiness() += this;
-        DoomsdayApp::gameProfiles().audienceForAddition() += this;
         Config::get("home.showUnplayableGames").audienceForChange() += this;
     }
 
@@ -191,6 +190,7 @@ DENG_GUI_PIMPL(GameColumnWidget)
         {
             if (profile.game().family() == gameFamily)
             {
+                DENG2_ASSERT(!findProfileItem(profile));
                 menu->items() << new ProfileItem(this, profile);
                 addOrRemoveSubheading();
                 return true;
@@ -326,6 +326,9 @@ DENG_GUI_PIMPL(GameColumnWidget)
             menu->setSelectedIndex(restoredSelected);
             restoredSelected = -1;
         }
+
+        // Observe further additions one by one.
+        DoomsdayApp::gameProfiles().audienceForAddition() += this;
     }
 
     void variableValueChanged(Variable &, Value const &)