Gui: Use auto and range-based for (#7481)

* On lines where the variable type is obvious from inspection, avoid repeating the type using auto. 
* When possible use a ranged for loop instead of begin() and end() iterators

src/Gui/SoTextLabel.cpp

@@ -481,7 +481,7 @@ TranslateManip::TranslateManip()
 {
     SO_NODE_CONSTRUCTOR(TranslateManip);
 
-    SoTranslate2Dragger *myDrag = new SoTranslate2Dragger;
+    auto myDrag = new SoTranslate2Dragger;
     setDragger(myDrag);
 }