IWizard and derived classes: Code cleanups

There should be no functional changes, just removal of unnecessary
code. This includes:

* Removal of unused QObject *parent = 0 parameters to constructors
* Removal of unnecessary explicits
* Removal of unnecessary virtuals
* Removal of unnecessary constructors/destructors

Some explicits were added though where those were missing.

Change-Id: Iab570349ea950dad0a2d01af17bc6175f70832f1
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/qmlprojectmanager/qmlapplicationwizard.h

@@ -61,7 +61,7 @@ class QmlApplicationWizard : public Core::BaseFileWizard
     Q_OBJECT
 
 public:
-    explicit QmlApplicationWizard();
+    QmlApplicationWizard();
 
     static void createInstances(ExtensionSystem::IPlugin *plugin);