Core: Cosmetics

* Remove redundant namespace qualifiers
* Qt5-ify some signal/slot connections
* Replace some using Core::Internal with explicit namespace scopes

Change-Id: Id1aae05e2c6fc2992c2716e1f8f9e985c6e56122
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/coreplugin/actionmanager/commandbutton.h

@@ -57,7 +57,7 @@ private slots:
     void updateToolTip();
 
 private:
-    QPointer<Core::Command> m_command;
+    QPointer<Command> m_command;
     QString m_toolTipBase;
 };