PinWidget and PortWidget

umbrello/widgets/pinportbase.{h,cpp}
- Factor new abstract base class PinPortBase from Portwidget and PinWidget.

umbrello/widgets/pinwidget.{h,cpp}
umbrello/widgets/portwidget.{h,cpp}
- Inherit from PinPortBase instead of UMLWidget.

umbrello/widgets/activitywidget.{h,cpp}
- New signal sigActMoved(diffX,diffY) is emitted when the activity widget is
  moved (cf. ComponentWidget::sigCompMoved).
- Reimplement UMLWidget virtual function moveWidgetBy() for adding emission
  of sigActMoved().

umbrello/widgets/widget_factory.cpp
- In function createWidget(UMLScene*,UMLObject*) case ot_Port, call
  PinPortBase::attachToOwner() on the newly constructed PortWidget.
- In function makeWidgetFromXMI() case tag == "pinwidget", call
  PinPortBase::attachToOwner() on the newly constructed PinWidget.

umbrello/listpopupmenu.cpp
- In function insertSingleSelectionMenu() case WidgetBase::wt_Pin add
  mt_NameAsTooltip. Set action checked if the object's floatingTextWidget()
  returns NULL.

umbrello/umlscene.cpp
- In function setupNewWidget() admit w->baseType() == WidgetBase::wt_Pin to
  call to PinPortBase::attachToOwner().

umbrello/CMakeLists.txt
- Add widgets/pinportbase.cpp to libwidgets_SRCS.

CCBUG:335399