Wizards: allows filtering of wizards based on Qt version

Every wizard now implements requiredFeatures() to define a feature set.
If the feature set is not satisfied by the available Qt Versions,
the wizard is not shown in the create file/project dialog.

Every Qt version can define the provided feature set in availableFeatures()
defined in BaseQtVersion.

Change-Id: Ie9e2c210d19187b2296451948c36d274f2096623
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>
Reviewed-by: Alessandro Portale <alessandro.portale@nokia.com>

src/plugins/vcsbase/basecheckoutwizard.cpp

@@ -147,6 +147,11 @@ void BaseCheckoutWizard::runWizard(const QString &path, QWidget *parent)
     }
 }
 
+Core::FeatureSet BaseCheckoutWizard::requiredFeatures() const
+{
+    return Core::FeatureSet();
+}
+
 static inline QString msgNoProjectFiles(const QDir &dir, const QStringList &patterns)
 {
     return BaseCheckoutWizard::tr("Could not find any project files matching (%1) in the directory '%2'.").arg(patterns.join(QLatin1String(", ")), QDir::toNativeSeparators(dir.absolutePath()));