"New Class" wizard: Add option for adding the Q_OBJECT macro

This lets users specify that a class derived from a custom base should
have a Q_OBJECT macro, and it also allows them to opt out of it for
classes derived directly from QObject & friends.

Fixes: QTCREATORBUG-21810
Change-Id: I850bd3bcb7b6eb71720afe5fa097178ff5d5c620
Reviewed-by: hjk <hjk@qt.io>

share/qtcreator/templates/wizards/classes/cpp/file.h

@@ -28,7 +28,7 @@ class %{CN} : public %{Base}
 class %{CN}
 @endif
 {
-@if %{isQObject}
+@if '%{AddQObjectMacro}'
      Q_OBJECT
 @endif
 public:

share/qtcreator/templates/wizards/classes/cpp/wizard.json

@@ -132,6 +132,17 @@
                         "checked": false
                     }
                 },
+                {
+                    "name": "AddQObjectMacro",
+                    "trDisplayName": "Add Q_OBJECT",
+                    "type": "CheckBox",
+                    "data":
+                    {
+                        "checkedValue": "AddQObjectMacro",
+                        "uncheckedValue": "",
+                        "checked": "%{JS: [ 'QObject', 'QWidget', 'QMainWindow', 'QDeclarativeItem', 'QQuickItem'].indexOf(value('Base')) >= 0 }"
+                    }
+                },
                 {
                     "name": "Sp2",
                     "type": "Spacer"