master compile failure

[Jonathan Riddell]

KDE neon is currently having a compile failure with Umbrello master
using KF5 build

http://build.neon.kde.org/job/xenial_unstable_applications_umbrello_bin_amd64/58/console

04:46:03 /workspace/build/umbrello/umlscene.cpp: In member function
‘UMLWidget* UMLScene::widgetAt(const QPointF&)’:
04:46:03 /workspace/build/umbrello/umlscene.cpp:956:45: error: no
matching function for call to ‘UMLScene::itemAt(const QPointF&)’
04:46:03      return dynamic_cast<UMLWidget*>(itemAt(p));