Enable deprecated API when using Qt 5.

The QAbstractItemModel::reset() method is deprecated in Qt 5, and
therefore not part of the API by default (on non-Windows).

The replacement for it is beginResetModel/endResetModel which are
available from Qt 4.6 onwards.

The minimum version of Qt required is currently 4.4, so enable the
deprecated API instead of changing that.

Source/QtDialog/CMakeLists.txt

@@ -25,6 +25,8 @@ if (Qt5Widgets_FOUND)
     qt5_add_resources(${ARGN})
   endmacro()
   set(QT_LIBRARIES ${Qt5Widgets_LIBRARIES})
+  # Remove this when the minimum version of Qt is 4.6.
+  add_definitions(-DQT_DISABLE_DEPRECATED_BEFORE=0)
 else()
   set(QT_MIN_VERSION "4.4.0")
   find_package(Qt4 REQUIRED)